Client|FontLineWrapping: Improvements and fixes

Better adherence to the maximum line width, and determining a specific
character's position.
Fixed|Client|GLTextComposer: Fixed internal logic and unsigned math errors

Also, allocated lines are not released if they haven't changed.
libgui|Drawable: Improved usability (named buffers, programs, states)
libshell: Added equality operator for Range
libdeng2: Use App's main clock for animations
Client|Widgets: Working on the LineEditWidget

Drawing the wrapped lines and a blinking cursor.

Todo: Fix cursor position issues.

Todo for later: Apply a visual style.