Added support for Cloudflare and multi domain support for namecheap

As featured at: https://support.cloudflare.com/hc/en-us/articles/200168816-Does-CloudFlare-work-with-Dynamic-DNS-Can-I-update-my-DNS-records-remotely-

Namecheap improvements: https://robertianhawdon.me.uk/2010/09/03/making-ddclient-work-with-multiple-domains-on-namecheap/
Could I see your ddclient.conf? Remove any sensitive data (API keys and usernames) before posting. Cheers.