fullscreen= now accepts the new value "2" for a fullscreen covering
only one screen. -geometry and geometry= now know additional keywords
"allscreens" and "onescreen".

Fixes ArcticaProject/nx-libs#923

This reverts commit 4eba4f53.

Attributes GH PR #984: https://github.com/ArcticaProject/nx-libs/pull/984

just as the rest of the Xserver is alsow doing

nxagentWindowTopLevel() and nxagentNeedConnectionChange() return Boolean
nxagentPixmapIsVirtual() and nxagentIsShmPixmap(), too.

They have been changed to tri-state variables (1, 0 and UNDEFINED)
between nxagent 1.5.0-90 and -93, for no obvious reason.

Many variables are used as Booleans. By adding the Bool define to
Options.h we can now make that visible.

and add the missing init code.

Adaptive, Composite, DeviceControl, DeviceControlUserDefined,
IgnoreVisibility, InhibitXkb, Nested, Menu, MagicPixel, Persistent,
Reset, ResetzKeyboardAtResume, SharedMemory, SharedPixmaps, Streaming,
UseDamage, ViewOnly, Xdmcp, Xinerama

The already where Booleans but where not using True/False values everywhere

There's no need/sense in having a tri-state with the third state being
UNDEFINED.