volk: fix CentOS build failure with extra lib64 in path

Use updated GrBoost.cmake from main build
wxgui: Fixes to solve issues using GL sinks on OS X
plotter/plotter_base.py: Create explicit OpenGL context, check if window is shown before realising context & only create PaintDC is paint triggered by WM message (OS paint event)
Added SetSizeHints to WX sink windows so sizing occurs correctly
blocks: fix file meta data source to handle repeat of files.
Merge branch 'maint' into v3.6.4git_gras_support
gras: use include for pmt_swig.i for swig vector error

Effected ubuntu 11.04 - the std::vector<unsigned int> already defined swig error

Import pmt_swig not include in all cases.

However, gr_feval.i was probably the one causing general to fail