Fix display of Spin Options with negative range
Let GTK dialogs open with actual-size Graph widgets

The Graph Option size values are now uses as size_request, to give
proper dialog sizing at popup. But the size_request is then reset
so that free sizing by the user becomes possible.
Ignore first configure event

The first configure event will be the one that adds the window decorations
to the board window, and must not be used to calculate a new square size,
but to expand the outer window instead.
Base new square size on board widget allocation GTK

No longer pay attention to the size of the top-level window, but base
everything on the size of the board widget itself.
Suppress duplicat autoInstalls

If the engine line constructed for -autoInstall already occurs in
the engine list, we should not install it again.
Fix variant-name recognition

StringToVariant did recognize whether the name to recognize had suffuxes
compared to the tabulated name, but not if it had prefixes. So 'shoshogi'
would be recognized as 'shogi'.
Prevent unknown variant getting button in -ncp mode

Normally we fake the engines play the requested variant, for the benefit
of engines that do not send a variants feature (e.g. v1 engines). But this
should not be done if there is no engine, as it would lead XBoard to
believe an unknown variant name is an engine-defined variant supported
by a currently loaded engine, and create a button for it in the New Variant
dialog.
mac: only use gtk compile flag, if gtk is enabled