moved all string options to std::string

*****************************************************************
WARNING: this has the potential to break things in subtle ways...
         PLEASE TEST AND REPORT ANY WEIRDNESSES
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get string option would NEVER work! Ugly fix until will replace all const char*
with std::strings in the options

Uniformisation of the weights of the Gauss Quadrature points (sum = volume of the reference element)
Adding Gauss Quadrature rule for a line
Modifications by Gaetan Bricteux

* point not found should NOT be an error in the octree

setNum() should change _globalNum

Amazingly, I have discovered a potentially serious bug in the routines
which perform edge collapse in the BDS_Mesh.

Owing to this, it is possible for a point to collapse onto a linear
boundary creating slivers (triangles with collinear points).

The problem is that the sides of the triangle, a and b, are not
recalculated after the point is moved.  Thus, area_final and area_init
are always equal!  So the test for slivers is defeated.

easy way to apply this to mesh/views unless we duplicate vertex arrays
anyway

-complete the doc of the GSHHS Plugin
-compile GSHHS plugin even if matheval is not present