Fix remark 1 in Bug #1393277 (the option "use absolute paths" acts reversed: ticked exports relative paths, unticked exports absolute paths)

* Make title capitalization consistant.
* Replace some instances of module with footprint.
* Use angle instead of orientation where appropriate.
* Remove abbreviations where it made sense.
* Coding policy fixes.

* Make "Drawing" string translatable.
* Add segment length to message panel.
* Add segment angle to message panel.

geometry: IsSolid() and Move() methods, segment overlap detection, some improvements in SHAPE_LINE_CHAIN class.

- fixed walkaround bug causing unwanted overlap/clearance violation when the first segment of trace being laid intersects the obstacle's hull at the same point twice (ie. goes in, turns around and goes out).
- fixed placer bug not splitting the start segment after toggling via placement or changing trace width

- re-worked PNS_LINE_PLACER and PNS_ROUTER classes a bit, removing duplicate class members
- cleaned up Andrew's blind/buried via fixes
- fixed 'custom via width' dialog bug updating the width even when closed/cancelled
- fixed incorrect radius of drawn microvias

Pcbnew: fix Bug #1391561 (PCBNew segfaults on BOM creation).  Does not happen on all platforms. Could be due to use of data just previoulsy deleted.
Very minor other changes.

pcbnew: Modules can be selected with block selection tool without including texts & references (GAL).

pcbnew: Allows selecting module edges in module editor, when they are covered with other items (GAL).

pcbnew: Fix persistent multiple items selection box that stays after selecting a polygon/line (GAL).

Minor doc update.

Apply patch from Cirilo Bernardo with some minor changes: mainly allows also the solder mask layer and keep ref and value fields on the silk layer.

* Fix assertions in Eeschema when editing net labels, electronic rules check,
  and plotting.
* Fix assertion when opening PCB calculator.
* Fix assertions in Pcbnew when changing footprints in footprint properties
  dialog and adding or editing text.

Polyline.h: remove useless class CRect. Use the more powerful EDA_RECT instead. Clean and remove duplicate code.

An ugly if-condition replaced with a CACHE'd cmake variable.