convert to UTF-8, eeschema cannot load LATIN1 strings anymore.

All source files are supposed to be UTF-8 now.  Although not a source file, my editor
was tripping on this file when grepping.

Pl_Editor: title block texts can be multiline (use" \n" :  a '\' followed by a 'n' to create a new line inside a text)
Very minor code cleaning.

* Force search when wrap past end of list option changes state.
* Fix SCH_FIELD::Matches() for bug in user defined fields which have an ID
  of -1.
* Minor improvements to the find data names to improve source code readability.

Eeschema: fix a *very subtle* bug noticeable only in complex hierachies, for multiple parts per package:
sometimes, the modified flag was set for these components just when switching from a sheet to an other sheet.
Pcbnew: fix Bug #1197414 (dragged track segments does not show clearance area)

This keeps it out of the KiCad mode path, making that leaner and less confusing about
what is supported in KiCad mode.  Within KiCad mode, treat quoted vs. non-quoted tokens
as the two general categories, with non-quoted having sub-categories.  Eliminate  
an unimplemented, unused function declaration in DSNLEXER.
 
Improve the output formatting of THROW_PARSE_ERROR().

in *.kicad_pcb file loading times.

Replace in EDA_TEXT::Draw the parameter EDA_DRAW_PANEL* aPanel  by EDA_RECT* aClipBox, which is the actual parameter used by Draw.
This change make more easy to  use this function when a EDA_DRAW_PANEL canvas is not used to draw texts.
Remove dead code in worksheet.cpp.

* Do not fail to build when wxWidgets is built with either --with-gnomeprint
  or --with-gtkprint are not configured.  Only display warning.
* Move warning code from include/common.h to common/common.cpp so it only
  shows the warning once instead of every source file that includes common.h

When KISYSMOD is not defined , in GetAllFiles, skip hidden directories
Gerbview: fix a collision name for GetLayout method.
Eeschema: fix potential crash when editing a pin electrical type (The user was able to enter a non existing type)