Fix161 - Align rows of Params Panel and Timetrack Panel

### Fix rows alignment
- Add a CellRendererText to TimeTrackView with same font attribute
to have same rows height.
- Add a CellRendererPixbuf at end of TimeTrackView (full alpha icon "utils_timetrack_align")

### Fix header alignment
- Hack the keyframe list and time slider widget's height by differentiating OS target with use of ifdef
- Remove (comment) a set_size_request on a cellrenderer

### Fix time cursors alignment
- Add two gtk::drawingarea widget inside the timetrack dock's to align the time cursors
- Draw orange time cursor before graduation in timeslide widget

#### Others
- Add a few comments here and there
- Comments about **potential memory leak** 090aefc
- Remove debug ouput