Updated AT_GetString-statements so the value is shown totally
(state before: Only first letter was shown)
Fixed getting cycle_mode-parameter: determination of EnumIndex was missing
Added is_sim_cam-flag, since there are parameters/functions/etc. that cannot
be used when a SIMCAM is addressed.
Added Error-Handling for invalid and unavailable access modes
of parameter requests and some code reorganising
Added handling of enumerated parameters (both: integer and string representation)
Further code reorganisation, removed some previous debugging g_prints