* 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
* add new docfield fetch_from - serves as add_fetch
* replace options.split with fetch_from.split
* copied data from options to fetch_from
* patch to update fetch_from for docfield, custom_field and property_setter
* update tests according to fetch_from change
* First approach by making a control
* Implement multi select for child tables
* Basic UI and items fetch in place
* Multiselect with checkboxes
* Functional modal with filters and new_doc
* Map filter fields to target_doc
* pass json arrays instead of strings
* Get items from quotation (in SO) working
* [minor] fix link route in list
* [minor] cleanup
* Add date, select first by default
* map_docs test, default date field
* [minor][fix] make new button bug
* [minor] move map_docs to erpnext
* [minor] format dates
