Documents task in changes log. Refs #2.
Displays info of selected cell next to the list. Refs #3.
Adds modification button. Refs #3.
Adds placeholder modal window. Refs #3.
Fixes sheet not appearing from parent window. Refs #3.
Renames EHHistory_vc to EHRoot_vc. Refs #3.

Since the vc is going to contain more than just the history.
Displays last row on load. Refs #3.
Implements modification of the date values. Refs #3.
Adds warning label for incorrect weights. Refs #3.
Adds locale aware float formatter. Refs #3.
Hooks return key to sheet accept button. Refs #3.
Updates model and GUI after modification. Refs #3.
Changes UI label. Refs #3.
Hooks return to accept button. Refs #3.
Documents task in changes log. Refs #3.
Merge branch 'feature/t3_modification_of_entries'