* invert failing lyx2lyx tests for ko/Welcome
* add dedicated test sample
* set language for English text part in ko/Welcome.
Also
* fix a lyx2lyx language test sample
* fix clause in unreliableTests
* New: support also utf8 (working around false positive test in "inputenc.sty").
* Do not force the change of input encoding to "ascii".
Deny compilation with XeTeX if a document uses TeX fonts and a non-supported input encoding.
Re-structure and rename files in a transparent way. Most template/example
names now correspond to the (verbose GUI) name of their layouts.
Note that this, most prominently, also changes [LANG/]splash.lyx to
something less insiderish, namely "Welcome.lyx".