* Remove six for PY2 compatability since our dependencies are not, PY2
is legacy.
* Removed usages of utils from future/past libraries since they are
deprecated. This includes 'from __future__ ...' and 'from past...'
statements.
* Removed compatibility imports for PY2, switched from six imports to
standard library imports.
* Removed utils code blocks that handle operations depending on PY2/3
versions.
* Removed 'from __future__ ...' lines from templates/code generators
* Used PY3 syntaxes in place of PY2 compatible blocks. eg: metaclass
* feat(control): Add Table MultiSelect control
* fix: Use btn-group instead of span
* fix: Remove functionality
* fix: Add 'Table MultiSelect' to Field doctypes
* fix: Replace usage of string 'Table' with array `table_fields`
* fix: Use internal array to store values instead of building from HTML elements
* fix(style): Add semicolon
* fix: Read only mode and click to navigate to form
* style: indent
* fix: fallback to empty array
* fix: Add formatters in js and py
* style: missing semicolon
* fix: Add docfield validation
* feat(markdown-editor): Add new fieldtype - MarkdownEditor
* feat(markdown-editor): Add MarkdownEditor control
* fix(markdown-editor): Fix placement of "Show Preview" button
* fix(markdown-editor): Render HTML in prints
