Eeschema: always stores sheet filename in unix-like notation, and fix a  bug when editing sheet file  name.
Pcbnew: add PDF format  for drill map generation.
Plotter classes: tweaking code.

All: remove macros  MAX, MIN, ABS from macros.h and replace these macros by std::max, std::min and std::abs (mainly found in old code).

SVG plotter: fix issues in draw arc and draw rectangle.