Upgrade golang.org/x/tools, drop Go < 1.11 support

b367e75 Limit the amount of memory errcheck uses with smarter goroutine scheduling
175c8b8 Drop support for Go 1.10 and Go 1.9
77437ce Upgrade golang.org/x/tools to latest
e327f15 Fix #139: Add example of excluding a call to a vendored dependency
ff9d777 Update .travis.yml
dd5e04e Update .travis.yml
aaeeb43 Use svg for ci build graphics
2050f4e Fix regression that occurs when GO111MODULE=on
f4fbc7c .travis.yml, tests: Update for GO111MODULE=on [ci-skip]
ff068b1 .travis.yml: Grow the build matrix, pin golang.org/x/tools version
3bf72b1 errcheck_test.go: Better error reporting for debugging
4f924b3 errcheck_test.go: Remove dead code