Don't perform extra go env calls in go/packages.
Load only needed go env vars in golangci-lint.
Stay in sync by enabled analyzers in go vet: remove nilness and
atomicalign analyzers, add errorsas analyzer.
Don't build SSA for govet.
Standalone govet runs 25% faster than before. All runs can be 5-10% faster
than before.
Relates: #208
1. Fix crash if deps of analyzed packages weren't compiled.
2. Print deps typechecking errors
3. Fix all issues filtering because of empty go env GOCACHE for go < 1.10
Use go/packages instead of x/tools/loader: it allows to work
with go modules and speedups loading of packages with the help
of build cache.
A lot of linters became "fast": they are enabled by --fast now and
work in 1-2 seconds. Only unparam, interfacer and megacheck
are "slow" linters now.
Average project is analyzed 20-40% faster than before if all linters are
enabled! If we enable all linters except unparam, interfacer and
megacheck analysis is 10-20x faster!
1. Rename in a backward compatible way
2. Remove gosec default exclude list because gosec is already disabled
by default.
3. Warn about unmatched linter names in //nolint directives
4. Process linter names in //nolint directives in upper case
5. Disable gosec for golangci-lint in .golangci.yml
