Building from release source code (installer method #2) does not set VE_HOME correctly

[jrawbits]

If an installation using the release source code is interrupted for some reason (e.g. the black screen of death I got during a recent test, unrelated to VE itself - it was a Teams issue for me that took it down), the VE_HOME and VE_SOURCE environment variables are not set correctly. There should be some way to reset those when R restarts from the directory used for the download.

The workaround is just to do the install again - the installer will recognize that you already have a downloaded version and the worst that will happen is that it will unzip everything again. It will want you to remove the "build-source" folder before you install again (don't delete the "download" folder to avoid having to download all over).

The future fix will entail creating startup files in VE_HOME that will enable starting R again to resume the build from the downloaded source.

[jrawbits]

An addendum to this issue. When building from source (and probably from a local clone), the set of built packages are not unloaded prior to ve.run(), which in turn prevents the framework from being unloaded. Consider updating the build script to unload each package after it's built.

The ultimate work flow will be to run ve.build, have VE_HOME updated with suitable startup files, and ensure that when ve.run() is used to start a recently built VisionEval, all the built packages are cleared first. Right now, there's no consistent way to restart R after doing a local build (and even runtime startup files are not being built since the startVisionEval function crashes before creating them due to built files not being unloaded.