rainx: use new librain interface, factorize code

Dependency updated to redcurrant-librain-0.7.1

Change-Id: I42306a1fd6b81ae2b15b5924596a782c75311081
m2v2,rainx: code cleaning, better memory management

Change-Id: I779c019f19ae11c29ad3e1bc3f185ad9595cc360