This commit adds service status to the query functionality for a single
service so that it doesn't have to be found in the full list of services.
It also adds the ability for the caller to control services using the
typical start/stop/pause/resume/restart style functions. To use these
functions the caller has to have appropriate rights.
Gathering of function pointers is now done during initialisation. This
means that it doesn't have to be done each time a function is called
and allows for reuse across other functions.
This commit adds the ability to enumerate services on the target machine,
showing the PID, the service name, the display name and an indication of
the service's ability to interact with the desktop.
Some other small code tidies were done too.
