[debug] renamed global functions that triggered E128

As per vim patch 7.4.260 [1], naming convection of user defined
functions are enforced (namely error code E128).
This commit renamed all those functions that begin with g: and were
followed by lowercase letters to g: with corresponding uppercase
letters.

[1] https://groups.google.com/forum/#!topic/vim_dev/M4_E1QhXVxA