Allow SCFG ciolib and uifc parameters to be read from ctrl/scfg.ini

If a sysop wants to override the default user interface/console I/O library
behavior of SCFG without using command-line arguments, they can create a
ctrl/scfg.ini file with the following optional [section] keys:

[uifc]
mode (advanced uses, e.g. disabling mouse support)
height (in lines)
insert (keyboard insert mode, not overwrite)
esc_delay (ESC-key delay)

[ciolib]
mode (advanced uses)
scaling (fractional values, e.g. 1.5, supported)
height (in pixels)
width (in pixels)

Command-line arguments take precedence over scfg.ini settings (if set).

The scfg.ini file is read *before* parsing command-line args, so if a ctrl
directory is specified on the command-line (e.g. rather than via environment
variable), the scfg.ini file won't be read from that specified location but
rather the default (/sbbs/ctrl) or the SBBSCTRL env var value.

Another attempt to make Nelgin happy and close out issue #749, though no, this
doesn't auto-save the current parameters (you'll have to create/edit the
scfg.ini file by hand).