add CBA_fnc_directCall

[commy2]

This is the best I can come up with.

required for #230

Makes the call atomic by reducing it to a pushBack.

can be confirmed working with:

TEST = {systemChat str (call CBA_fnc_isScheduled)};

call TEST;
0 spawn {
    call TEST;
    TEST call CBA_fnc_directCall;
};

-> false
-> true
-> false

Name does not conflict, because the old one is named CBA_common_fnc_directCall

[commy2]

Performance test:

new:
cba_fnc_directCall
10000/10000
0.0880981 ms
0.0400024 ms

old:
cba_common_fnc_directCall
1175/10000
1.49186 ms

The old one also breaks when used twice in the same frame. (Only the last directCall would be used)