We don't need to use a regular expression to find "goN.M" anymore,
as go/version seems to deal with "devel" versions from master just fine.
We can then also stop having two separate fields for the version
of the Go toolchain currently being used.
Which can be helpful when debugging assembly build errors
such as the one from #948.
I could not get an obfuscated binary to ever print or show its
assembly positions or filenames, so this has no test.
* reflect_abi_patch.go was added into reflect.go
* shared.go was renamed into cache_shared.go and package caching was moved to cache_pkg.go
* transformer methods in main.go are moved to transformer.go
