generator: simplify bool logic in Method class

There are two elements repeated in this expression:

(( ((A) || (B)) || (B)) && C)

We can simplify "(A || B) || B" to simply "A || B",
so the result is a bit more readable this way:

(A || B) && C
generator: drop unneeded parameter in WriteLine() call
generator: leverage framework's String.IsNullOrEmpty() call

This makes the code a bit more readable and it is a
micro-optimization.
glib: fix warning

`t` was not being used.
Merge pull request #82 from knocte/cleanup

Various small cleanups in generator and glib