Add -profile option, remove unnecessary type conversion and output more detailed error messages

[mewmew]

The -profile option was present before but has since been commented out, add the option back to enable profiling of gocc.

An unnecessary type conversion was located by unconvert in the generated code of parser/parser.go

-               errorSymbols := p.stack.popN(int(p.stack.topIndex() - rs))
+               errorSymbols := p.stack.popN(p.stack.topIndex() - rs)

Last but not least, change the error handling so that extended error values don't lose extra information when reporting errors. For instance, using errors from the errors now reports the full context of the error.

[awalterschulze]

Looks good, except for:

errcheck ./...
main.go:203:23: pprof.StartCPUProfile(f)
make[1]: *** [errcheck] Error 1
make[1]: Leaving directory `/home/travis/gopath/src/github.com/goccmack/gocc'
make: *** [travis] Error 2

Do you think we should maybe even delete the profiling, or do you want to use it?

[mewmew]

Do you think we should maybe even delete the profiling, or do you want to use it?

We can delete it, and I'll add it locally when playing with performance tuning.

[mewmew]

There we go, the -profile flag has now been removed.

[awalterschulze]

Could you regenerate?

And maybe its time to upgrade the go version that is being tested in travis?

[mewmew]

Could you regenerate?

Done.

And maybe its time to upgrade the go version that is being tested in travis?

Also done.

[awalterschulze]

Thanks, this is a nice cleanup :)