Remove Nuria::MiniLexer

MiniLexer has been superseeded by Nuria::Tokenizer and the lemon LALR
parser generator tool shipped in Twig.
Callback: Fixed reversed logic for (non-)blocking inter-thread invoke

Callback will use a QueuedConnection for SLOT() invocations on QObjects
outside the current thread if the slot returns 'void', or a
BlockingQueuedConnection if it returns something. The logic for this
was the other way around.
Callback: Allow manually setting the Qt::ConnectionType on SLOTS()