+ add openjpeg-dev as dependency
+ change buildtype to be optimized on size
+ disable debug (like plain buildtype)
+ the issue with luajit has been fixed
+ add commented-out buildir variable and sed on $pkgver to ease testing with alphas.
As of now we're using the buildttype 'release', which produces optimized builds
but without any usable debugging info, which makes debugging crashes impossible,
even if a -dbg subpackage exists. As such we should build in the buildmode
'debugoptimized' to offer proper debug symbols.
