merge configuration options of @ulikoehler

[elrido]

As requested by @Hexalyse in PR 87: Merge the changes of @ulikoehler from PR 63. The goal is to provide configuration options for many of the features.

Some of these points might already be available in the current state of the project. Will have to review them point by point.

[ulikoehler]

Definitely thumbs up from me!

[elrido]

Ok, so If I understand the all changes correctly, they provide these features that are already provided in this fork:

• configurable minimum time between posts in seconds (rate limiting) - check
• configurable maximum post size - check
• configuration to disable the discussion system - check
• configuration to enable the syntax highlighting - check
• configurable time periods - check

Regarding these points I have some questions:

• default expiration time - It is possible to select something invalid or nothing at all for the expiration. There is a proposed configuration for what to use in such a case. Currently we degrade to the default selected value if this happens. I think this is the simpler and cleaner behaviour then having a separate option. But if anybody can provide a solid use case for a separate option it can of course be merged.
• configuration to disable the display of the hash on-screen - Could somebody explain me what is the use case or what it protects against? I see the danger that users might not think of copying the URL from the browsers address bar instead. On the other hand side if it is a configuration option we can set a "sane" default and whoever wants to use it can simply disable it.

Let me know what you would prefer on these two points.

PS: I added some documentation in the wiki.