Increment line count even if line is ignored

[JeanMertz]

If a line was configured to be skipped, the line count was not incremented, resulting in the wrong offending lines to be reported back to the user.

[codecov-io]

Codecov Report

Merging #6 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master       #6   +/-   ##
=======================================
  Coverage   72.72%   72.72%           
=======================================
  Files           1        1           
  Lines          55       55           
=======================================
  Hits           40       40           
  Misses         10       10           
  Partials        5        5

Impacted Files	Coverage Δ
lll.go	72.72% <100%> (ø)	⬆️

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[JeanMertz]

The remaining build errors are related to Go 1.5. I haven't dug into the issues (not sure if it's worth it for such an old Go version), but here's the output:

$ go get -t -v ./...
github.com/alexflint/go-arg (download)
github.com/alexflint/go-scalar (download)
github.com/walle/lll
github.com/alexflint/go-scalar
github.com/alexflint/go-arg
github.com/walle/lll/vendor/github.com/alexflint/go-arg
# github.com/alexflint/go-arg
../../alexflint/go-arg/parse.go:157: field.Tag.Lookup undefined (type reflect.StructTag has no field or method Lookup)
The command "eval go get -t -v ./... " failed. Retrying, 2 of 3.
github.com/alexflint/go-arg
# github.com/alexflint/go-arg
../../alexflint/go-arg/parse.go:157: field.Tag.Lookup undefined (type reflect.StructTag has no field or method Lookup)
The command "eval go get -t -v ./... " failed. Retrying, 3 of 3.
github.com/alexflint/go-arg
# github.com/alexflint/go-arg
../../alexflint/go-arg/parse.go:157: field.Tag.Lookup undefined (type reflect.StructTag has no field or method Lookup)
The command "eval go get -t -v ./... " failed 3 times.

[walle]

I'm sorry for taking this long to get to the PR, but it is finally in the
project as part of the v1.0.0 release.

Thank you for you contribution!