Set ASCII support to “True” for cz and sk keyboard layouts

(from Vratislav Podzimek)
Support reading gzipped xml files

Suggested by Vratislav Podzimek.

Saves a lot of space for the installed files.

I try to read <datadir>/file.xml first now, if that does not exist
<datadir>/file.xml.gz, if that does not exist either, ./file.xml and
if that still doesn’t exist ./file.xml.gz.
Add tt_Latn and tt_Cyrl
Accept script names as used by glibc locales as well

I.e. accept also “latin” instead of “Latn”.

(Suggested by Vratislav Podzimek).
Release 0.0.5.