FB should continue working even if cvar/ directory is missing or it is empty
Re-enabled cvar env init after Vasily's patch
Removed assert that would terminate correct runs

avd_get_int is used on unitialized variabled (e.g. randdist_init), so
the assert would terminate correct runs. In the future, we should
consider whether *_get_* functions should handle these cases or not.
Tab randvars should have var_type of VAR_RANDOM
Enabled seed attr for tab randvars
Aligned comment blocks to 80spc limit in fileset.*
Modified delay flowop to support nanosecond delays
Removed 'help' and 'usage' commands
Added UofT copyright in COPYING
file/fset defs shouldn't accept unsupported attrs
Renamed fileset_define() to fileset_alloc()