Sanitise incoming GAL config options using mapping tables
When reading config options from files, it's important to make sure the
value makes sense - the incoming data could be anything, and may have
incompatible values or be otherwise unreliable.
This introduces a simple way to define and use "mapping tables" which
can map between a "native" value, probably an enum (but not necessarily)
and some external value, for example the value written to file.
This provides a decoupling between the two values, as well as sanitising
inputs and outputs. This is important, as over time, if there isn't a
decoupled interface, changing options result in corrupt configs, or a
proliferation of obsolete enum values kept for compatibility.
Add protected virtual dtor for GAL_DISPLAY_OPTIONS_OBSERVER
GAL_DISPLAY_OPTIONS_OBSERVER aren't deleted by a base class pointer -
they are an "incidental" part of other classes. Add a virtual protected
destructor to make this explicit.
This allows the user to set a thicker grid line without causing the
grid lines to become over dense, or just make the grid denser according
to preference.
The term "density" is modified to "minimum grid spacing", which is
the pixel spacing between adjacent grid lines.
The spacing settings now comes in along, with other GAL display settings,
as part of GAL_DISPLAY_OPTIONS observer functionality. To this end, the
setter in GAL interface is removed, as an external user should be
setting this parameter via the GAL_DISPLAY_OPTIONS interface.
Add grid line thickness control to Display Options Dialog
This adds a user-settable control for the grid line thickness on GAL
canvases to the display options dialog.
The thickness settings now comes in, along with other GAL display
settings, as part of GAL_DISPLAY_OPTIONS observer functionality. To this
end, the setter in GAL interface is removed, as an external user should
be setting this parameter via the GAL_DISPLAY_OPTIONS interface.
Add a class to govern an "incrementing" text control
This class, INCREMENTAL_TEXT_CTRL, is used to provide a frameworks for
classes that want to control a text control that can be incremented
according to some scheme.
Also provided is a wxWidgets implementation with spin buttons for
control, as well as mousewheel support.
Break Display Options control value/enum mapping to functions
The mappings from enums to control settings can be done in static
functions, which makes the set/retreive functions more concise, and also
puts the mapping functions in a clearly delineated place.
This puts the graphical/display options with the other similar options
in that dialog, rather than with the dimension options found in the Set
Grid dialog, which is in the Dimensions menu.
Also place the option itself in the GAL Display Options structure, so it
can be updated using the observer mechanism there.
The setter for the style in the GAL interface is removed, as the public
interface for setting this option is now to modify the
GAL_DISPLAY_OPTIONS structure and notify the GAL when done.
