New app.http high level wrapper

[synopse]

A new class may be defined to run a stand-alone HTTP(S) server easily.

Including most out-of-the-box nginx features:

• HTTP and HTTPS support with custom certificates or Let's Encrypt service;
• three execution models: Apache (one thread per HTTP/1.1 connection); Async (IOCP or epoll); http.sys (Windows only);
• static content delivery, with optional gzip compression;
• direct pascal code execution at low-level HTTP;
• direct pascal code execution as SOA callbacks;
• redirect to a TRestServer instance (the previous SOA item may be transparently implemented with this);
• HTML server-side rendering using Mustache and our MVC pattern;
• CGI/FastCGI execution #388 ;
• reverse proxy at TCP level #387 ;
• optional IP black list for 4 seconds on status code error, and global CDIR blacklists built-in support;
• customization of the whole workflow using pascal.

The idea is to define the class parameters as high-level methods in pure pascal code, using our efficient router class. Later on, we may see if external settings (using YAML or somewhat compatible nginx format) may also make sense.