Set version of the MCM

[rs028]

Implement a way to switch between versions of the MCM. At the moment this is hardcoded in the build python scripts. Only the files in the mcm/ directory are involved (peroxy radicals list and photolysis rates parameters).

EDIT: possible solutions:

1. use symlink
2. add a switch to the build.sh script (see also Use flags for the build script #416)
3. add an option to a configuration file (eg, model.parameters)

[rs028]

• check that the peroxy-radicals_* files are complete (done by Correct lists of RO2 (v3.2, v3.3.1) #356 and mcm lists #361)

• find photolysis-rates_v3.2 (done by mcm lists #361)