xxcat: improve scripts, remove bashism
build: convert to non-recusrive make
maint: improve scripts with 'usage()' and 'die()' functions
scripts: improve with 'usage()' and 'die()'
scripts: ppsx: merge ppsx/psx/rsx, step 1
scripts: merge psx/rsx/ppsx into one script

* Makefile.am: add install-hook target to create symlinks to
  'rsx' and 'psx' from 'ppsx'.
* scripts/ppsx: operate based on detected script name.
scripts: update copyright/license/email, change to GPLv3+
scripts: 'make_balloon' - improve usage(), portabiltiy
scripts: improve usage() function