Merge pull request #159 from hgolsen/master

CRA-738 Added rock physics for singe interval
CRA-743 Removed some bugs in rock physics
Merge pull request #160 from ulvmoen/master

CRA-743 Removed some bugs in rock physics
CRA-505: Minor fix for multizone.
Merge branch 'master' of git://github.com/CRAVA/crava into CRA-738
CRA-505: Reading of rmswell and norsarwell assumed that the wells had a TWT-log.