Fixed Push and Shove and ratsnest cooperation (tracks added by PNS are taken into account while calculating ratsnest).

Items removed from board are removed from ratsnest as well. Corrected the way of items removal from ratsnest.

[MacOSX] Added support in boost context for PPC processors, now is possible again compile kicad testing for PPC ( https://svn.boost.org/trac/boost/ticket/8266 )

Pray for angus johnson who is support too many languages, and needs to find a text editor that removes trailing whitespace.

Pcbnew: very minor fixes and update:  update clipper version. uncrustify polytri/* and fix some warning compil.

Switch to boost::context for all platforms, almost.
Please try your platform by commenting out fcontext.s in common/CMakeLists.txt.

[MacOSX] fixes issues with previous OSX compilers gcc-4.2 and makes a better general beaviour of KICAD_BUILD_STATIC

eeschema: fix compil issue. Boost build: boost lib context built only on OSX (does not build on mingw, and not needed)

(https://svn.boost.org/trac/boost/ticket/8266)