Rename $rcorefilename -> $rcorebasename

Value in the variable is actually not a file name, only its leading part
omitting .tmp, .rcore.lzo or other suffix. The new identifier better
reflexes the value's purpose.
Reintroduce $rcorefilename

Now really denoting name of the resulting rich core file.
Test case UUID support.

Reads test case UUID from file created by testrunner-lite and creates
marker files to link up test cases and crash reports.