Adopy

* A minor fix on retrieving version information with `importlib-metadata`.

* Drop support for Python 3.5.
* **(breaking change)** `adopy.base.Task` takes labels of response variables as the argument `responses`. Instead, the possible values for the response variables should be given to `adopy.base.Engine` as an argument named `grid_response`.
* **(breaking change)** `adopy.base.Model` takes a log likelihood function for an argument `func` now, instead of the probability function for a single binary response variable. The log likelihood function can take multiple response variables.
* **(breaking change)** The `compute` method in `adopy.base.Model` provides the log likelihood function now, instead of the probability of a single binary response variable.
* Using multiple response variables is available now!
* `adopy.base.Engine` now can update multiple observations, given as a list of designs and a list of corresponding responses into code:`design` and `response` arguments, respectively.
* Now, you can choose what datatype to use for `adopy.base.Engine`, with an argument named `dtype`. The default is `numpy.float32`.
* Remove unused types at base (26; contributed by NicholasWon47).

A minor version update due to PyPI configuration. It has the exact same features as ADOpy 0.3.0.

**The first version that is released publicly.**

- **General changes**
- Now, we fully updated the README file and documentation.
- Example codes are provided in the `/examples` directory.
- **Base classes** (`adopy.base`)
- Possible responses (`responses`) are now stored in task classes (previously in Engine classes).
- The engine class gets a new function, `reset()`, in order to reset an engine object to an initial state.
- **Choice under risk and ambiguity task** (`adopy.tasks.cra`)
- Two design variables, `prob` and `ambig`, are renamed to `p_var` and `a_var`, respectively.
- **Delay discounting task** (`adopy.tasks.dd`)
- The module name for the delay discounting task is changed to `adopy.tasks.dd` (previously `adopy.tasks.ddt`), in order to make it consistent to other tasks (e.g., `adopy.tasks.cra`). Also, the task and engine classes are renamed to `TaskDD` and `EngineDD` (previously `TaskDDT` and `EngineDDT`).
- 4 design variables are renamed to `t_ss`, `t_ll`, `r_ss` and `r_ll` in order to make it consistent to notations in math equations.
- In all model classes for the DD task, `tau` (inverse temperature) is ordered as the last parameter.
- The model class for Generalized Hyperbolic model, `ModelGH`, is renamed to `ModelHPB` for Hyperboloid model.
- **Psychometric function estimation** (`adopy.tasks.psi`)
- The task class for a 2-alternative forced choice task is renamed to `Task2AFC` (previously `TaskPsi`). N-AFC task will be supported in future updates (see Issue 18).
- The model class with a shape of Normal CDF is renamed to `ModelProbit` (previously `ModelNormal`).

- Support only for Python 3.5+, excluding Python 2.7.
- Rename `adopy.tasks.psi.TaskPsi` to `adopy.tasks.psi.Task2AFC`.
- Add docs powered by Sphinx.

- Fix `adopy.functions.get_nearest_grid_index` which had made posterior updating malfunction.
- Use `autopep8` instead of `yapf` for develop environment.
- Fix staircase implementation for Psychometric function.