Fix minor whitespace and comment issues in rebar_utils
Adapt arch string to versioning scheme changes (>= 17.x)
rebar_utils:otp_release/0: handle vsn like x.y.z**

As mentioned in the OTP documentation, licensed customers may use
patched OTP installations where the otp_patch_apply tool adds a '**'
suffix as a flag saying the system consists of application versions from
multiple OTP versions. When we get such a version string, we drop the
suffix, as we cannot obtain relevant information from it as far as
tooling is concerned.
Merge pull request #327 from tuncer/fix-326

Adapt arch string to versioning scheme changes (>= 17.x)
Follow-up typo fixes for #327
Merge pull request #328 from tuncer/typos-in-327

Follow-up typo fixes for #327
Add {prefix, atom()} option for abnfc_opts

Specify the atom to use as a prefix for the decoder and generator
functions inside the parser's module.  Default is ''.
Add {parser, module()} option for abnfc_opts

Specify the module to use for parsing the ABNF grammars.  Default is
'abnfc_rfc4234'.
Add {qc, proplist()} option for abnfc_opts

Specify the options to use for the generator functions inside the
parser's module.  Default is [].