pathmap semantics issues

[David Taylor]

Okay, here's some questions concerning how pathmap should behave:

. should it translate all paths?  Or just some paths?  If some, which?
Source paths?  Others?  That is, should it be consulted when looking
for sources?, objects?, executables?, and shared objects?

. should it be searched instead of the existing path?  Or in addition?
If in addition, which should be searched first?

Do people care?