Formatted all sources and manually tuned some files to make the code look neater.
See script directory for method. The script to run in the top level MaxScale directory is called maxscale-uncrustify.sh, which uses another script, list-src, from the same directory (so you need to set your PATH). The uncrustify version was 0.66.
Fixed all warnings that were present with -Wextra.
Take almost all warnings into use except `format-overflow` and `unused-function`. format-overflow needs to be handled in a separate commit.
