fix parse array with the external const correctly (golang#569)

Fixes golang#561 - Panic on array parsing if length is externally defined

It also fixes the following minor problems in TestParseArrayWithConstLength, a test function related to this feature.

It doesn't check all outputs to be asserted.
It doesn't initialize some of the fields in mockgen.fileParser, even though they are initialized in the production code. (Actually, it caused an unnecessary test error by test data I added)

fix issues related to source package imports (golang#507)

Fixes: golang#505
Fixes: golang#515

remove rsc.io/quote/v3 as dep

Revert "Fix golang#71 Do + DoAndReturn signature change error msg (go…

…lang#395)" (golang#413)

This reverts commit f9b4ad1.

don't ignore stdout.Write err (golang#410)

Improve performance of mock generation (golang#397)

Optimizes resolving correct package name with `go list` command. Instead of calling go list for each import in file, now we do it for all imports in one call.

fix not resolving go module major versions (golang#385)

This change now makes use of go list to check for package names. This
tool is module aware and allows for better named imports.

To test this change I needed to also add a small package to our mod
file. To keep this import from disappearing from go.mod I made use
of the tools file strategy.

Note this change will change the import names in generated code. This
should not be a breaking change in user code.

Fixes golang#326

ci: adds check to ensure go modules are up to date

Tidy up module dependencies

gomock: refactor directory name

Rename directory to match default package output of gomock.