Test for the case sensitivity of methods when doing reflection.

We should preserve the case sensitivity of the function when doing reflection
so that we can use the results to call instance methods. This is needed by
libraries like Mockery where mock objects are created dynamically.

Addresses #1624.
When storing the methods defined in the class, preserve case.
Preserve case when listings methods defined by a class.

Addresses #1624.
Fix the casing for all of PDO and PDOStatement's instance methods.

Addresses #1624.