Warn/limit user from adding widgets that aren't available in the version of wxWidgets the project is set to use

[KeyWorksRW]

Description:

We already have problems with C++ supporting two versions of wxWidgets, and wxPerl may end up with 4 supported versions, and we are about to start supporting content that is only available in wxWidgets 3.3. It's going to be confusing to choose a widget which displays fine in Mockup but doesn't show up in the user's program because they are linked to an older version of wxWidgets. The Mockup issue would at least mitigated if we popped up a warning any time the dev tries to add a widget that isn't supported in the version of wxWidgets they indicated they were using. We definitely need to start getting something in place that deals with this problem.

One way to deal with this is if the widget isn't supported in the project's version, then we could popup a dialog asking if the dev wants to change the minimum project version. Once there are versions of the other languages that support wxWidgets 3.3, that will be important for them as well.

For SVG files, we should probably do something similar once the image is selected -- at least for as long as we support any language that allows a version of wxWidgets older than 3.2.

For properties, we could simply look at the preferred language and it's wxWidgets version and either not show, or disable properties that require a newer version.