Improve .gitignore rules.

A '.*' rule prevents the 'git submodule add' from correctly adding the
first submodule, because it creates the .gitmodule file.  This file will
not be added (without -f) result in incomplete submodule commits.
The new rules mask the specific files present in my own build tree, but
additional rules may be needed to hide other types of temporary files.

.gitignore

 # stuff "git status" should ignore
 
 # build output
-.*
+.libs
+.deps
 *.o
 *.a
 *.lo
 *.la
 *.in
 
+# editor files
+*.swp
+
 startup_tcl.c
 xscale_debug.h