Sherpa Prototype

Feature
- insert new buttons are working
- modify selection buttons are working

Feature
handling insert new... blank line button

Feature
handlers for "Edit Selection" buttons group are there

Refactoring
minor aesthetic stuff in ProgramView.js

bugfix
made sure all buttons are enabled when there is no selections; e.g. right when doing page_reloaded

Refactoring / Feature
modified ProgramView.js -> prepareSelectables -> genHandler so we are now displaying all the "modify selection" buttons regardless of selection but we are disabling the non-relevant ones as needed.
This allows for the UI to remain the same thus preventing user from having to located every time the options they are looking for in the ever-modified list of buttons

tried to keep selection highlighted during tab switches
turns out we lose the highlight & probably the selected / lines / ... attributes as they are re-generated by renderStatements
temporary solution is to remove the btnEditPanel buttons so we don't show them without selections

Refactoring
Moving functions from edits.js to appropriate models / views

Feature
ProgramView.js genHandler is now able to populate buttons based on selection
Might be a good idea to keep the list of buttons fixed but just disable the non-relevant ones with some CSS & appropriate neutral handlers in the future

Features
adding support for button panel allowing users to modify the selected lines