Dtale

* hotfix for dash custom.js file missing from production webpack build script

* [75](https://github.com/man-group/dtale/issues/75): added code snippet functionality to the following:
* main grid, histogram, correlations, column building & charts
* exposed CLI loaders through the following functions dtale.show_csv, dtale.show_json, dtale.show_arctic
* build in such a way that it is easy for custom loaders to be exposed as well
* [82](https://github.com/man-group/dtale/issues/82): pinned `future` package to be >= 0.14.0

* support for google colab
* [71](https://github.com/man-group/dtale/issues/71): Filter & Formats popups no longer have smooth transition from top of screen
* [72](https://github.com/man-group/dtale/issues/72): Column Menu cutoff on last column of wide dataframes
* [73](https://github.com/man-group/dtale/issues/73): Describe popup does full refresh when clicking rows in dtype grid

* [77](https://github.com/man-group/dtale/issues/77): removal of multiprocessed timeouts

* centralized global state

* allowing the usage of context variables within filters
* [64](https://github.com/man-group/dtale/issues/64): handling for loading duplicate data to dtale.show
* updated dtale.instances() to print urls rather than show all instances
* removal of Dash "Export to png" function
* passing data grid queries to chart page as default
* added sys.exit() to the thread that manages the reaper