initial implementation of Runtime Type Identification
added test file for RTTI
fixed pfield setting for subinstruments and UDO's
modified get_arg_string() read from the root instrument instance's strarg (fixes bug where UDO's could not read strings from pfields)
further enhanced RTTI test
Merge branch 'develop' into feature/rtti
turn of freeing of CHNENTRY->data in delete_channel_db(), as data is tracked either directly when channel is created, or is part of CS_VAR_MEM that is calloc'd elsewhere (and should not be freed)
Merge branch 'develop' into feature/rtti
Merge branch 'feature/rtti' into develop