Added new type aliases and convertion functions.

Here are some more type aliases for the types I keep encountering with IPP dap functions. Many of them may seem trivial, but I've been bitten by complex numbers a few times. Take a a function with a suffix of `_64fc`, I could either type `Complex128`, or `Complex{64}`. More than once I wasn't thinking and wrote `Complex64`.

One thing to note: for types I followed the convention of `IPPInt`, `IPP64fc`, etc. It seems cleaner to me, and is easier to type since you only have to hit shift once and hold it for 3-4 characters. It would break some code in IPPMath, but a search and replace would fix that. Since you started these packages, I'll defer to your judgement as to what style to use.