The previous Makefile is doing "cp *" and hence installing uninteresting
files like the Makefile itself.
Copy only the application-relevant files, and switch to using install
for some of this where we can automatically create parent directories
if required, solving issues when installing into an empty root.
locale installation is optional; as before, locale files will be
installed if they are present, but installation can also proceed
without them.
By default the Makefile installs data into /usr/share (with default prefix
/usr) but the binary is installed into /usr/local/bin (as if the prefix
were /usr/local).
Improve consistency by dropping "local" from the binary path. If the
user wants to install into /usr/local he/she can do PREFIX=/usr/local
Currently the Makefile lets you choose your own PREFIX, but
the installed runanki.system always hardcodes the prefix as /usr.
Fix runanki.system at install time to install into the designated
PREFIX.
