[PATCH 0 of 2] reduce possibility of skipping check-code when not desired

[Simon Heimberg]

check-code.py was skipped on entire files by accident.

The current pragma "no-check-code" was accidentally used in code (in check-code.py itself).
Patch 1 adresses mainly this by requiring "# no-check-code".

Patch 2 adresses the problem of skipping the entire file instead of skipping only one line.
The pragma must be in a comment on a separate line. And it must be near start of file 
(as in polib.py) or near end of file (as in httpclient).