Merge pull request #748 in CASA/casa from CAS-7555 to master
* commit '83ecfca27cbfe2181c703ad9b1327b84c28e920c':
minor text edit
Fixed a crash with multiterm and mosaic virtual model
Fixed some indexing error
Re-wrote the mapping of data selection to the record of ftmachine or componenlist stored in the ms as virtual column. The selection now includes scannumber and stateid This is labelled as version 2 of the virtual model vis. version 1 of the model vis is still supported for reading. Once support is removed the code can cleaned and reduced.
