TAS: Trim leading/trailing spaces from channel name
This fixes TV logo lookup for channels with leading/trailing spaces
WebMP: Show channel logo as preview image in flash player
WebMP: Use case-insensitive usernames
Library: Prefer the configured service address above all other methods

The old behavior didn't make any sense: there is no reason why the configured address
shouldn't be used if an IP address couldn't be detected. If an address is configured, always use
it now.

Thanks to Ollienator for noticing this behavior.
WebMP: Add configuration options to override base URLs

Instead of jumping through hoops by using reverse proxy rewrite rules for
external access, this provides the option to just override the base URLs
sent in replies.

(cherry picked from commit 1eba84685fd91b4924e69d546b80492a584f7429)

Conflicts:

	Libraries/MPExtended.Libraries.Service/WCFUtil.cs
	Libraries/MPExtended.Libraries.Service.Config/Services.cs
Hosting: Fix initialization of WCF services
WebMP: Add overloads accepting Uri instances to ExternalUrl
WebMP: Add method for generating artwork links to UrlHelper
WebMP: Show preview images in HLS player

Inspired by a patch from Ollienator, thanks!
Merge branch 'fixes-from-ollienator'