Fix classloader and parser handling for libraries, add tests

[BlazingTwist]

I've found a good excuse to write an aya library and discovered some oversights in #111

• StaticData no longer releases the classloader used to load libraries
  • this avoids a ClassNotFoundException when libraries have multiple classes (such as DataStorage in the example library)
• NamedOpToken now no longer throws a ParserException for "undefined" namedOps
  • libraries could be loaded at any time, so a ParserException does not make sense anymore
  • instead, the opName is checked when the Instruction is executed
• to verify that this actually works, an example library is compiled and imported during the maven test phase
  • (if you'd prefer, I can move the test/example library to /examples instead)

[nick-paul]

The ParserException was definitely an oversight on my end. The tests look great too. Thanks!