docs: Restructured intro page, added some manual pages
Merge remote-tracking branch 'mbant/docs/structure' into docs/structure
build: adding fstream include files for pedantic compilers.
qtgui: bringing in line with required Qt 4.4.

setGraphicsSystem was introduced in 4.5; doing a version check before its use.
Merge branch 'maint' of git.gnuradio.org:gnuradio into maint
Merge branch 'maint'
docs: minor updates to the docs, including a new page for Python blocks.
Merge branch 'docs/structure'
docs: fixed typo in portaudio
docs: fixed use of section tags in python_blocks docs.
docs: Added LaTeX packages for better math docs
blocks: Nicer LaTeX docs for multiply_matrix