commitmonitor Code

Remove the "using namespace std" statements and explicitly refer to the std namespace where needed.

* add an empty line after the license header
* remove unneeded empty lines at the end of files
* use the right case for the includes
* always use <> for system headers
* update ext/Versions.txt

convert tabs to spaces.

Indicate the GPL license.

Delete all diff files when a monitored URL is removed.