Id must be run from home directory or it can't find files

[LegalizeAdulthood]

The compile definition SRCDIR is supposed to fix this but it doesn't seem to be working correctly. I suspect only some of the files are located through the mechanism that falls back to SRCDIR.

There is the environment variable FRACTDIR mechanism as well, but I don't think that's been tested to see if it works properly, either. Either way the variable should be renamed to ID_HOME.

This relates to bug #92 as well.