First (raw) integration of the OneFeel student project into Feel++.
The project aims at interfacing Feel++ applications with Gmsh through OneLab.

Changes:
- Added onefeel.sh script used to configure the necessary OneLab files and launch Gmsh,
- Added --generate-ol option to Feel++ options,
- Added code to generate OneLab files from command-line options.

Fix:
- Removed duplicate entry in command-line options (gmsh.domain.recombine)

Known issue:
- Don't put commas in configuration entries, it messes up Gmsh OneLab parser for now.