ert test enhancements

- fix: s/go-test-verbose-mode/go-test-verbose/

- support for testing within emacs (ala M-x ert)

- add test/go_test.go for use with tests

- ert test go-test-get-current-file

- ert test go-test-get-current-test
Workaround go test -file

While 'go test' has a '-file' argument, it isn't actually supported.
See the source for src/cmd/go/test.go:
  "testFiles        []string   // -file flag(s)  TODO: not respected"

Workaround this by generating a regex for tests in the current file
and pass to 'go test' via the '-run' flag.
Add compilation-error-regexp support

A compilation-start-hook is used to override the default
compilation-error-regexp-alist to provide explicit error
matching for go test related errors.
Make sure go-test-current-file uses a test buffer

Example: if current-buffer is named 'foo.go',
switch to buffer named 'foo_test.go'