Added three new functions for selections:
expandtoline    - selects the entire line for each line in a selection (newline included)
joinSelection   - joins selected lines into a single space-delimited line
invertSelection - inverts all selected lines
Changed the name of the "joinSelection" function to "joinlines".
Also changed it's behavior so that when there is no selection, it will join with the next line.
Updated ExpandToLine, JoinLines, and InvertSelection based on feedback.
Merge pull request #1 from AMiniLegend/selection-features

Selection features updated
Merge pull request #1976 from AMiniLegend/master

Added three new functions for selections: