style fixes
fix usage of url-* functions
Fix cache invalidation for dangling operator cache

We made two mistakes here:
1) we didn't add the hook correctly, which caused it to be lost when syntax-ppss installed its hook
2) we didn't correctly create a new hash and instead set it back to itself
use line-number-at-pos isntead of count-lines

count-lines would return a wrong line number if point is at the
beginning of a line
do not use dangling op cache when buffer is narrowed
add some documentation
in go-packages, skip over directories that do not contain a /pkg subdirectory
nicer messages in gofmt
style fixes
use correct regexps for labels

labels don't only consist of word characters but also unicode and underscores
disable read-only on error buffer before trying to write to it
Use completing-read in godoc--read-query
Merge branch 'master' of https://github.com/imarko/go-mode.el into imarko-master