- new dir.c function: Dir_FindHereOrAbove:
Search for a path in the current directory and then all the directories
above it in turn until the path is found or we reach the root ("/").
- add hooks to use it in main.c for -m and syspath (compiled in
_PATH_DEFSYSPATH and $MAKESYSPATH).
- updated man page
search list that will be used. Thus 'dot' and 'cur' will appear in
${.PATH} either at the start or end depending on .DOTLAST even though
they are not strictly in dirSearchPath.
When .CURDIR is assigned to - re-set the 'cur' Path.
Finally, when checking subdirs, look in 'dot' and 'cur' (first or last
depending on .DOTLAST) just as we do in other situations.