Config to ignore interfaces

This release adds the config parameter ignoreInterfaceRegexps, which provides the ability to specify regex patterns which will ignore calls through an interface with a matching name.

For example:

ignoreInterfaceRegexps:
- [dD]ecoder

The above configuration will cause errors returned by methods called on an interface named decoder or Decoder to skip wrapcheck analysis.

Many thanks to @guillaumeio for the contribution!