* add In annotation
* remove struct forward declarations
* fix members initialization list in header
* merge removal code for function bodies and constructor definition
Move all scalebar rendering code out of composer and ensure that
all scalebar rendering is done independant of QgsComposerScaleBar
This allows scalebar rendering code to be reused by plugins
and by non-composer code.
Also rename QgsScaleBarStyle -> QgsScaleBarRenderer, (and all
subclasses too). This name better reflects what these classes do.