Work on user based control

Test file shadow (password matches username *cough*) for login purposes.

When a user gains FCGI_LockControl, a directory is created (if it doesn't exist).
Control_Handler will operate from the directory of the currently logged in user.

The user who owns the currently running experiment must match a user who wants to control it.
Alternately an administrator can pass "force"

Consider generalising this to also apply to actuators (since any user can change the actuator control :S).

Also it's horribly messy and terrible and all in the Control_Handler at the moment.

FCGI_Context should probably store a lot of the information that the g_controls structure is storing at the moment? Merge/replace?