Ecmath

Added an EcMath class, which accepts a numeric value or a PointInterface.
Added an interface, covering add(), mul(), getDouble(), mod(), and cmp(), and result(). 

There are tests for the EcMath class, mainly just asserting some operations like (k+k)*G = (k*G)+(k*G). 
Test.php has some examples of usage. (Private/Public classes are not the classes used in this library)

The library tolerates you trying to add an integer to a point, by carrying out the point multiplication when required. 
It will throw an exception if you try to do something impossible, like multiplying two points together.

I haven't added an equals() function, like the Point and Math class both have, though I will probably add this shortly.  Also want to refactor the Math, EcMath, and Crypto components into namespaces, after we discuss it.
Actually, perhaps I'm wrong about the debug decorator. Just thinking, if the mathAdapter you're using were wrapped in a debug decorator, it'd be nice to pass it into the EcMath class and debug that.

Do we need a function on each of BcMath and Gmp to act as the factory? Or we could declare a static method in the MathAdapter interface that would take an instantiated MathAdapter and produce the EcMath object?