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!
lll is using scanner.Scan() to read the file line by line.
scanner.Scan() might fail if the line is longer than bufio.MaxScanTokenSize
In the case where the specified maxLineLen is smaller than bufio.MaxScanTokenSize
we can return this line as a long line instead of returning an error.
The reason for this change is that this case might happen with autogenerated files
The go-bindata tool for instance might generate a file with a very long line.
In this case, as it's a auto generated file, the warning returned by lll will
be ignored.
But if we return a linter error here, and this error happens for an autogenerated
file the error will be discarded (fine), but all the subsequent errors for lll will
be discarded for other files and we'll miss legit error.
