Backport 2.0 work

[alcaeus]

This PR back-ports a bunch of 2.0 work to 1.x:

• Drop copyright headers #200 (Drop copyright headers, @Majkl578)
• Drop SimpleAnnotationReader #199 (Drop SimpleAnnotationReader. This PR deprecates it for future removal)
• Fixed typo in the documentation  #208 (Typo fix in documentation, @azjezz)
• Change Annotation::value typehint to mixed #209 (Change Annotation::value type to mixed, @malarzm)
• Document correct method usage #217 (Document correct method usage, @greg0ire)
• Update homepage #221 (Update homepage, @Majkl578)
• Mention coding standard requirements in the README #239 (Mention coding standard requirements in the README, @sanmai)
• Extract implicitly ignored annotation names to separate class #242 (Extract implicitly ignored annotation names to separate class, @Majkl578)
• Add all PHPUnit annotations to the globally ignored list #254 (Ignore all PHPUnit annotations, @jrjohnson)

As for the rest of the 2.0 work, I'll work on back-porting #256 first. This is going to be a little trickier as we need to make it backward compatible (as we can't have hard BC breaks in this kind of library). After that, I'll go through remaining PRs that are in the 2.0 milestone and back-port them as necessary.