This allows to concatenate multiple vectors and single elements into a
single result vector.

Add suport for using unicode strings in .scad files. Support iterating
across them/accessing them via [] and searching.
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Add GLIB (to build for test and normal build -- both with installed and
built locally development files).
Add support for unicode chars to length and search builtin functions and
[] for strings.
Added unicode testing functions.
Ad GLIB to library info page.