* translation system and unit tests
* Translations everywhere
Dont use translation merge
It is not available with PHP builtin gettext, so it would have lead to inconsistency.
Modifications
- rename `pageCache` to `CachedPage`
- move utilities to `Cache`
- do not access globals
- apply coding rules
- update LinkDB and test code
- add test coverage
Signed-off-by: VirtualTam <virtualtam@flibidi.net>
