This fixes the perl compilation failures of fullPathName.pl
that occur before the src/tools directory has been built, and
ensures that the other tools that use EPICS modules also work.
Removed the -h option to convertRelease, use $ENV{EPICS_HOST_ARCH} instead.
Reworked variables associated with expandVars to make it simpler to use.
Split EPICS::Utils module into three parts.
Moved code from fullPathName.pl into the new EPICS::Path module.
Changed convertRelease.pl to use new modules.
Added some documentation to RELEASE_NOTES.html