Better organized examples.

doc/lua_api.md

include/libgmshdg/gmsh_io.h

include/maxwell/maxwell_interface.h

include/maxwell/maxwell_postpro.h

share/capacitor/capacitor.geo

share/capacitor/capacitor.m

share/examples/capacitor/capacitor.geo

share/examples/capacitor/params_capacitor.lua

share/examples/microwave_oven/oven.geo

share/examples/microwave_oven/params_oven.lua

share/examples/modeconv/modeconv.geo

share/examples/modeconv/modeconv.i1

share/examples/modeconv/params_modeconv.lua

share/examples/yagi/params_yagi.lua

share/examples/yagi/yagi.geo

share/examples/yagi_rad/params_yagi_rad.lua

share/examples/yagi_rad/yagi_rad.geo

src/libgmshdg/gmsh_io.cpp

src/maxwell/CMakeLists.txt

src/maxwell/maxwell_interface.cpp