COMPLETE REFACTORING. v2.0.0

Compatible with v1.0.0

editor:
highly improved search/replace dialog with flags (f3 key).
add menu for duplicate and move lines.
fix bug with completion widget and scrolling.
fix bug with move line at the first line.
place common code in utils.py.
refactor code, make it more compatible with python 3+.

classes:
add attribute expressions (python code).
explicit declare modification flag here.

widgets:
add high featured json widget for editing any json data.
use code editor for editing button commands.
use label/code templates for button widget.
improve generic UI experience, add placeholders.
add increase/decrease size for text widget.
fix curve default value (get rid of tuples).
show slider for lineEdit when a validator is used, default min/max 0-100.
fix radioButton widget column number selector.
a lot of code refactoring.

ui:
edit attributes expressions within their context menu.
edit attributes data with json widget.
improve modification flags experience, now works more consistent.
highly improved visual style for attributes with connection/expression.
add ModuleItem which solely work with Module class using Qt data mechanics.
remove main menu, use instead improved context menu.
add copy tool code menu to obtain the code for running the module as a tool.
RigBuilderTool arguments fixes: child supports int/str, size supports number/list[2] to specify the tool's window size.
completely refactored code to make it more compatible with python 3+.

utils:
common functions/classes live here.