Update Compare Document

.. to reflect feedback from Damien re compare sets

.. Also changed the compare pane to be view specific and
   shared across all charts in the view.
Add GPS/Altitude alignment to Compare spec

.. we should make it possible to display interval
   data aligned via the altitude or gps data as well
   as via time/distance. This really only applies to
   the ride plot.
Compare Pane Mockup

.. balsamiq mockup and png export
Forgot message in compare pane mockup
Basic Compare Pane Hide/Show

.. just committing before adding animation and the compare pane content.
Remove qDebug() from TabView.h
Fix events shown on LTM plots

Recent update to change the way the LTM configuration dialog
worked accidentally lost the events setting.

Show events is not being stored in the LTMsettings 'datastream'
but as a separate chart property -- but *is* stored internally in
the LTMSettings class.

it was being lost when the datastream is appled. This fix makes
sure the value is remembered and reapplied after the settings are
applied.
Compare Pane 'hpos' property

Introduce an hpos property on TabView::mainSplitter so we can use
an animation to make the compare pane slide up and down when
arriving and leaving.

Will add the animation shortly, just pushing to save updates.
Compare Show Animation

.. need to fix hide timeout animation but do that
   later tonight.
merge master into personal