Loader: add includes max nesting level

[trejjam]

• bug fix? yes
• new feature? yes
• BC break? no

Pull request for #162. Solving possible call stack overflow.

[trejjam]

For code style error created issue https://github.com/nette/coding-standard/issues/28

[dg]

Does it make sense to include one file more than once (nested)? Ie. has sense to have INCLUDES_MAX_DEPTH larger than 1?

[trejjam]

I was thinking about it and it is possible that someone use config like:

config.neon:

includes:
  - console.extension.neon
  - config.extensionRequiresConsole.neon

config.extensionRequiresConsole.neon:

extensions:
  vendor.name: Vendor\Name\DI\Extension
includes:
  - console.extension.neon

It is probably easy to remove this 'mess' from config, but I think it is basically not wrong.

[dg]

I think it's better to add and remove files in the $loadedFiles and then only test the presence.