CD workflow - build (but do not release) release candidate artifacts.

[dmalec]

To set some context- I'm submitting this PR with the thought it may assist in the overall 6.2 release process. If it's more of a disruption at this point, I can close the PR and work on this as a post-6.2 idea (no worries either way :) ).

I've tried to break down the change into three rough categories below; but, am also going to add a few comments in places where I'm particularly uncertain about the changes I made. To get a sense of what it looks like in action: https://github.com/dmalec/ucblogo-code/actions/runs/430995787

(You can view the workflow anonymously; but, do need to be logged into GitHub to download the artifacts)

CD features:

• Builds and caches wxWidgets for three target platforms - Linux, OSX, Windows
• Builds on Linux, producing the PDF, source tar.gz, and source .zip
• Builds on OSX and Windows, leveraging the the PDF from the Linux build
• End state should be 5 artifacts - PDF, .tar.gx, .zip, .dmg, .exe

CD motivated changes:

• Allow overriding of MinGw bin directory and wxWidgets directory in makefile.msys
• Added -static flag to LDFLAGS in makefile.msys
• Removed -lctl3d32 from LIBS in makefile.msys
• Commented out makelib and Messages build targets in makefile.msys

6.2 specific changes:

• Added VERSION to config.h.msys
• Added -DHAVE_CONFIG_H to CFLAGS and CXXFLAGS in makefile.msys
• Updated OutputBaseFilename to ucblogo62setup in inno/ucblogo.iss
• Updated PDF/texi filename from usermanual. to ucblogo. in inno/ucblogo.iss and makefile.msys

[jrincayc]

Thanks, that looks useful, I'll review it more later.

[dmalec]

I think I'm closing in on the next revision - hoping to have an update by end of day.

[dmalec]

As long as the changes I've made in makefile.msys don't disrupt local builds, I think this is "there" from a GitHub runner machine perspective.

[jrincayc]

Is this ready for merge?

[dmalec]

Is this ready for merge?

@jrincayc - yes, this is ready for merge.