Pcbnew: fix bug in drag module: connected tracks were not dragged.
worksheet: code cleaning.

remove "~" from empty *.lib component fields, replace with "", doctor old *.lib fields to blank if that was the intention

Remove duplicate code to draw and to plot title blocks  (more than 1500 duplicate lines). Note: this is a work in progress.
Code cleanup

* Add code for loading, modifying, and saving the global and project
  footprint library tables.
* Add code to load MODULE objects using the footprint library table to
  the footprint viewer.
* Add static methods to FP_LIB_TABLE to support loading footprint library
  tables.

Code cleaning and move worksheet code specific to title block and frame references shape in title_block_shapes.h and title_block_shapes_gost.h

Pcbnew: fix bug 1179877, due a bad default  copy constructor, after  my changes about CPOLYGONS_LIST class.
More about CPOLYGONS_LIST work.

Pcbnew: fix minor bug about  plot line width.

* Fix a bug when full file name and path are passed to FOOTPRINT_INFO::
  ReadFootprintFiles() which I created in bug fix lp:593989.
* Fix a wxString debug assertion in EDA_APP::InitEDA_Appl() when the KICAD
  environment variable is defined as an empty string.
* Add error dialog when libraries cannot be found in system search path
  when loading footprint using the select footprint dialog.
* Add footprint library name column to the EDA_LIST_DIALOG when selecting
  footprints from the list.
* Allow reading all columns from the selected row in EDA_LIST_DIALOG.
* Remove redundant sort from EDA_LIST_DIALOG constructor
* Add library name member variable and accessors to FOOTPRINT_INFO.
* Make headers translatable for Eeschema select component from list dialog.
* Add some helper methods to FPID for identifying the FPID type and validity.
* Remove a bunch of trailing whitespace and add missing license comments.

Eechema: fix bug : when saving the schematic project, the lib cache was saved under the current sheet opened, not the root sheet.
Pcbnew: clamp default plot line width between 0.02 and 2 mm. the other bug (saving this parameter in internal units instead of mm is not fixed)

(explanation: float is implicitly promoted to double anyway, it's only useful
for storage; also a fp variable forces conversion of other int in the expression
without needing a cast)
Typo fixes in some comments 'floatting' -> 'floating' :D

Mass parameters in gerbers can't use scientific notation (altough some software 
allow it), so the %g format was not correct.

A specctra layer is not a LAYER_NUM, so that's probably why it was difficult to use.

The plan goes like this:
- eeschema still uses int in decidegrees
- all the other things internally use double in decidegrees (or radians
  in temporaries)
- in pcbnew UI the unit is *still* int in decidegrees

The idea is to have better precision everywhere while keeping the user with int i
angles. Hopefully, if a fractional angle doesn't come in from the outside, everything
should *look* like an integer angle (unless I forgot something and it broke)

When the time comes, simply updating the UI for allowing doubles from the user should
be enough to get arbitrary angles in pcbnew.

This is a starting point of some code enhancements relative to polygons in Pcbew and 3D viewer.

Adds "kicad_pcb" to the list of file-extensions for PCBnew in its Info.plist 
to make Launch Services recognize the file associations.

Change 8 bit string to UTF8 so fancy mew in "um" can be shown. 

Note: ArcTangente gives a double but *takes* ints, so it's not good to
use for nontrivial things