Dtale

* resizable columns
* updated how click loader options are found
* Added loader for r datasets (`*.rda` files)
* updating the language menu option to list options dynamically

* [452](https://github.com/man-group/dtale/issues/452): handling of column names with periods & spaces as well as long names
* updated styling of windows to match that of Charts
* [448](https://github.com/man-group/dtale/issues/448): set default value of "ignore_duplicate" to True
* [442](https://github.com/man-group/dtale/issues/442): Dash Updates
* Split charts by y-axis values if there are multiple
* Saving charts off and building new ones
* Toggling which piece of data you're viewing
* Toggling language nav menu
* Instances popup changes
* updated preview to use DataPreview
* updated display of "memory usage" to numeral.js

* Updated MANIFEST.in to include requirements.txt

* [445](https://github.com/man-group/dtale/issues/445): updated URL paths to handle when D-Tale is running with jupyter server proxy
* [315](https://github.com/man-group/dtale/issues/315): Internationalization (supports english & chinese currently)
* [441](https://github.com/man-group/dtale/pull/441): Add option to 'pin' the menu to the screen as a fixed side panel
* [434](https://github.com/man-group/dtale/issues/434)
* updated scatter plot date header to be generated server-side
* updated scatter plot generation in correlations to use date index rather than date value for filtering
* update setup.py to load dependencies from requirements.txt
* [437](https://github.com/man-group/dtale/pull/437): optional memory usage optimization and show mem usage

* [428](https://github.com/man-group/dtale/pull/428): Turn global_state into interfaces
* [434](https://github.com/man-group/dtale/issues/434): Additional PPS formatting
* [433](https://github.com/man-group/dtale/issues/433): fixed exception message display in merge UI
* [432](https://github.com/man-group/dtale/issues/432): updated calls to "get_instance" in merge code snippets
* [431](https://github.com/man-group/dtale/issues/431): fixed stacking code example
* [430](https://github.com/man-group/dtale/issues/430): replace empty strings with nans when converting dates to timestamp floats

* [261](https://github.com/man-group/dtale/issues/261): Merging & Stacking UI