Initial commit for rewriting the Fortran API

- Removes non-standard DEC$ directives
- Changes comments to F90 (!) from F77 (C)
- Adds semver major, minor, patch variables
- Changes semver version to a larger string
- Changes docstrings to be Doxygen abiding
- Changes module name from `gmsh_fortran` to `gmsh`
- Changes file extension from `.h` to `.f90`
- Changes indendation to 4-space (fixed for now)
- Fixes & being erroneously placed at the start of newlines vs EOL
- Reformats variable commas, spacings, etc. to be consistent
- Removes hardlimit for procedures names> 45 to be excluded from the API

TODO List:
1. Abide by `indent`, currently spacing manually set to 4spaces
2. Add optional arguments for things such as `gmshModelAddPhysicalGroup`
3. Change names _n _nn to more descriptive names
4. Simplify spacing between procedure types
5. Convert API names to be user friendly get, set, etc.