Reaction-plane-fit

Note the API changes introduced by moving the fit results to the components!

Added

- Store errors on fit parameters. See: `fbb9bd36cf7f4b010377cb1c1d27cb5d09ccf57d`.
- Evaluate the background function of a component. For a background fit component, this is the same as the fit
function, while for a signal fit component, this will describe only the background contributions. See:
`8836a38cbdb44f6db1508a23f295ff4872433938`.
- Preliminary instructions on running the fit via c++. They are not yet tested. See:
`8f6d57ca160e9500b4fa5c2747faa9e4b23c5a12`.

Changed

- Moved component fit results into the fit components. See: `a08c42a483d51ba5c599986ae8f5cdec6a4505f0` and
`51ef75007d2a765bd03bf01958517d3109140067`.
- Moved fit evaluation into the fit component. This was enabled by moving the fit results into the fit
components. See: `e3c13956b80ad31b7232f46fe0784b0179462175`.
- Moved `FitType` to the `base` module so that it is more easily accessible. See:
`f3513c9f3d01d51c46e6b776fad005c32864001d`.
- Moved error calculation to fit component. See: `674c8cf0f3bff1ebe95a8d5b76a7c2917d3169b7`.
- Refactor error calculation to allow it to calculate errors for both the fit and background functions (or any
other function). See: `674c8cf0f3bff1ebe95a8d5b76a7c2917d3169b7`.
- Improved example plot styling. See: `eb9fe16bd19e1e0106a822ee7e6a31f8a9be7e51` (included with a few other
minor changes).
- Determine and plot errors on residual. See: `74b7f14b34b37b3563dcebc1031730a9343b5252`.
- Large improvements to typing information and documentation in a variety of commits.

Fixed

- Background fit example legend placement was accidentally moved. See:
`1869eb0650c9b26157c6fed103e80e5ad78f7f08`.
- Baseline test images, which started failing after a number of small aesthetic changes. See:
`795d9d228a5cde6d5477dfd1c697efcabec7547c` and `33f9dd83f5918ba5f5eabd86b78759df1197a9ac`.
- Failing tests due to floating point variations in calculating parameter errors. The comparison tolerances
had to be loosened. See: `e668599966df447e99de7c145ad6c97ce7d2d814` and
`f2729a4c5ed517b25fd99019f71ccabf65bd2ac5`.
- Indicate that the package is typed. The typing information is already there - it just didn't know it
propagate it when running `mypy` on other packages. See: `b113e40be09705fdc3f4cce1a6ea7bbcaa14442a`.
- Updated call to the old `pachyderm.Histogram1D` API. See: `f23f31473b77203e3c2d5cf9d2617c4f3f53a6db`.

Removed

- `evaluate_fit_component(...)` from the `ReactionPlaneFit` object. It is unnecessary given the API changes.
See `5e2048eb1bace3d34dd428aea79b7ca002e61156`.

Added

- Added `mypy` to Travis CI checks. See: `3fe44b42773b7b6d4fa184cf8db82a5e529713e0`.
- Pre-commit hooks configuration to the repository based on `pre-commit`. This should generally improve the
quality of commits. Currently includes `flake8`, `mypy`, `yamllint`, and some additional minor python
checks. See: `e0218dffc0829ac742790497b5f0494bd41c0035` and `a40c72e42cb50bf0658c871e8ea8d3f0aa5b393e`.
- Ability to run Minos errors. They aren't stored (because it doesn't make sense to do so), but they can be
compared to Hesse errors. See: `b0149099bc4e05a0e4f37d78680abe5ed4fa7ff3`.
- Allow for user arguments to override the fit arguments. See: `bf570c37163b57c02d890aa5047f99e8bb82077c`.

Changed

- Adapted to new pachyderm histogram API. See: `c6b17fe6555d7baab3be9cb53c4f238bd8e23b65`.
- To implement the new API, it required some relaxation of array comparison tolerances (but they are still
quite stringent). See: `631db84754b1d03076acc24ea5ab9bdae88bcb38`.
- Renamed "inPlane" -> "in_plane" (and the other angles accordingly) for better matching of conventions (which
makes it easier to use and integrate with other packages). See: `300258f77f2ebd9f83754ab1d0f41e028e95032f`.
- Updated RP plot labeling for new RP orientation naming convention. See:
`7a9e939f442a73e96349583553228d923341109a`.

Fixed

- A number of type annotation issues identified by `mypy`. See: `8b71c77f99f8d95fd364bc7a700e2a32ecbdb499`.
- Test discovery failed in some cases. See: `85e5ad0f2a6ab4d55393167c9289018061826f37`

Added

- Test the `FitComponentResult` objects in the integration tests. See: `dcb21966`.
- Updated documentation.
- `mypy` to the dev requirements. Although not run in the CI (because not all of the identified issues are
actually issues), it is good to have available and run from time to time. See: `bdc216a7`.

Changed

- Refactored `Histogram` class to pachyderm, where it was renamed `Histogram1D`. See: `923c3847`.

Fixed

- Resolved a tagging problem related to a rebase.

Added

- Zenodo DOI information.
- Chi2/ndf calculation.
- Plot module (with tests) to draw the fit and the residual.
- The tests take advantage of image comparion.
- Additional fit quality checks.

Fixed

- Parameter argument ordering in the signal inclusive fit. See ba4e833a.
- Fixed error propagation by calculating the error for each individual component rather than for the
simultaneous fit (which was the wrong approach). This has the side effect of substantially speeding up the
error calculation.
- Specify all initial parameters, limits, and steps, which can substantially improve the chi2.
- Various type annotations.

- This is essentially a preview release.
- It can perform the RP fit using background only data, including the reaction plane orientation inclusive
signal, or the reaction plane orientation dependent signal. Full error propagation is performed for each
fit component.