Feature/gmsh write settable variables

See merge request tools/frackit!208

[python][brepwrapper] add ctor from shape wrapper

See merge request tools/frackit!209

Feature/cleanup common

See merge request tools/frackit!207

the rotate() function has been moved to the geometry module, and the
wrappers for toDegrees() or toRadians() have been removed as Python
offers such functions

The functions are self-explanatory and the way it was rendered in
Doxygen was not really helpful. This makes the Doxygen page more
readable.

Feature/cleanup-examples

See merge request tools/frackit!206

Feature/rename cmake functions

See merge request tools/frackit!205

[python][ex2] avoid warning, set mesh size in domain

See merge request tools/frackit!204

[status] fix percentage output to two decimals

See merge request tools/frackit!203

Feature/improve gmsh writer

Closes #17

See merge request tools/frackit!202

Feature/improve entity networks

See merge request tools/frackit!200

[status] suppress warning if no target was set

Closes #22

See merge request tools/frackit!201

One can now set mesh sizes for individual geometries and furthermore,
one can define geometries to be physical or non-physical, depending on
which the interior of the geometries is explicitly meshed or not.