Added types to private functions, improved readability, shouldCheckProxyHeaders as separate function

[akrabat]

This is #38 with main merged into it.

Proposed some minor improvements/changes:

• added argument and return types to private functions parseWildcard, parseCidr, getFirstIpAddressFromHeader
• improved isValidIpAddress function readability
• moved determining whether proxy headers should be checked to separate shouldCheckProxyHeaders function