refpack and refpackset paths should be relative to parent file, not base directory
I guess everyone has their install files in the same location as their install content so this doesn't cause an issue, but we have our install xml files in a different location from the install content and use the -b command line parameter to point to the install content, but then when our main install xml file uses a refpack to import another pack the compiler tries to locate the referenced file relative to the base directory, not the parent install file and fails.
It would seem to me that in either situation it would be better for a pack that uses a refpack or refpackset that the location of the referenced file should be relative to the install file itself and not the base directory. And assuming existing sites have their install xml files and content in the same location this should be a non-breaking change.
It was a relatively simple update to the compiler to include the parent directory of the main install file in the CompilerData and have the CompilerConfig use that directory try resolve referenced files rather than the base directory.