Fixed '#include's (appied most of 'include-what-you-use' suggestions).

Fixed '#include's (appied most of 'include-what-you-use' suggestions).

The worst dependency which 'include-what-you-use' fails to see
(and rightly so) is 'src/parse/lex.re' -> 'src/parse/parser.h'.
This dependency is caused by '#include "y.tab.h"' in 'src/parse/lex.re'.

Another ubiquitos issue is 'src/util/c99_stdint.h' ('include-what-you-use'
suggests to substitute it with '<stdint.h>').

And a couple of other dependencies that 'include-what-you-use' fails to see.