Add specification for strings

[Kampfkarren]

Strings

This specification requires the addition of strings and chars. Note that topics such as string concatenation, formatting, etc are not mentioned as, in true PHP fashion, they should be their own functions in the global namespace.

[ghost]

topics such as string concatenation, formatting, etc are not mentioned

These should be available to strings with double quotes and not to strings with single quotes. To make this less impossible when creating a CIC, there should be two types: single-string and double-string.