Fix minor bug #1429990 (3D viewer shows hidden footprint graphic texts ). Fix minor coverity warnings (not initialized members and dead code)

class PLOTTER: dash lines parameters in one place for plot. I made minor changes (values in mm and set to give the same size as dashed lines drawn by wxDC, using short dash.)

Fix a few minor coverity warnings.

Moved "Place Target" and "Place Module" tools from DRAWING_TOOL to PCB_EDITOR_CONTROL (to avoid placing modules in the footprint editor).

Fix issue #1429665 (eeschema doesn't recognize .sch file when the LIBS section is empty. But the section is not used, just a comment, therefore can be empty).
Very minor other fixes.

Eeschema now uses dashed lines for graphic lines (to be consistent with plot functions and toolbal icon).
Fix an old bug in some envionments which warp the mouse on a bad monitor when opening eeschema, pcbnew and some other windows, only noticeable guys who are lucky enough to have more than one monitor.

 - CACHED_CONTAINER::GetVertices: removed useless and unused function
   which does nothing but tainted the API
 - SHAPE_LINE_CHAIN::Collide( const BOX2I& aBox, int aClearance ):
   removed an outdated function with assert(false)
 - SHAPE::BBox(): fix a small typo in the doc string

Minot fixes: Minor coding style issues fix (tab -> spaces). Add missing GetClass to all classes derived from EDA_ITEM. Make debug method Show() only compiled in debug mode.

Minor fixes: coding style in 3d-viewer and minor code cleanup, and some fixes in bom python scripts, which did not work when a non ascii char (but a valid utf8 symbol) was found in xml netlist. Add comments.

* Fixed incorrect parameter ordering in gEDA footprint library parser
  which read drill diameter, pad clearance and solder mask clearance.
* Fix FindOpenSSL.cmake version detect bug which was exposed by OpenSSL
  version 1.0.2.

Fix some coverity and cppcheck warnings (most are very minor issues: not initialized members and initialized but not used variables)

The hotkey import/export files have now the extension ".hotkeys"