file module doesn't support utf-8 file names

[Vlad Dumitrescu]

Hi,

with the recent addition of utf-8 support, there are high expectations
about where utf-8 values are allowed.

One of those is in file paths, where the file name is types as a
string(), but the file:file_name/1 utility function only allows
characters between 0 and 255. I think that just allowing integers up
to 65535 should fix this.

Similar issues seem to be present in epp.erl, erl_comment_scan.erl,
erl_tidy.erl and igor.erl.

best regards,
Vlad