Trikit

* Pinned dependencies in requirements.txt.

* Additional Pandas compatibility changes.

* Updated deprecated Pandas and Numpy methods (applymap, append, etc.)

* Removed instances using Pandas lookup method.

* Added `load_lrdb` function dedicated to CAS Loss Reserving Database data.

* Added amz09 loss triangle.

* Added `get_quantiles` method to MackChainLadderResult and BootstrapChainLadderResult.

* Added `devp_corr_test` method to `MackChainLadderResult` in order to test for development period correlation.

* Added `cy_effects_test` method to `MackChainLadderResult` in order to test for calendar year effects.

* Added `diagnostics` method to `MackChainLadderResult`. Produces faceted quad plot with reserve distribution,
development by origin and standardized residuals by development period and origin.

* Changed `totri` trignale type argument from `type_` to `tri_type`.

* Cumulative triangle `cl` method no longer supported. Chain ladder methods available to cumulative triangle
instances can now be accessed via `base_cl`, `mack_cl` and `boot_cl`.

* Medial LDF averages are included when calling a triangle's `a2a_avgs` method.

* Added MackChainLadder implementation.

* Added PP Auto, Workers Compensation, Medical Malpractice, Product Liability and
Other Liability lines of business to CAS Loss Reserve Database.

* BaseChainLadder method can now accept arbitrary LDF patterns, and is not limited
LDF patterns computed from the data directly (patterns available `tri.a2a_avgs`)