Update io.h

Fix message "io.h:36:19: warning: no newline at end of file"
Update io_module.h

Fix message "io_module.h:42:7: warning: no newline at end of file"
Update introduction.rst

Typofix: "Cadence"
Update simulator_support.rst

Typofix: "Cadence"
Update Makefile

Small rewording to prevent throwing off simplistic syntax highlighters.
Update io.h

Fix missing underscore in comment.
Merge pull request #151 from cmarqu/master

Small fixes for: typos, warnings about missing newline at EOF, syntax highlighting