Added getter for cameraID

Added getter to Interpreter for cameraID
Refactored LUDecomposer

Made the LUDecomposer stateless. It now passes around a
DecompositionResult to wrap the data that was previously (ickily) stored
internally. Modified LinearSystemSolver to accomodate the new function
call.
Implemented Interpreter Tester

Added a whole one test case that tests whether the constructor correctly
saves the cameraID it is provided with.
Error handling for LUDecomposer

Made many functions print messages and return null when they receive
invalid input.
Extended LinearSolverTester's test cases.

Added invalid angle list test case for LinearSolverTester
Merge branch 'development' of https://github.com/Threepud/Sketchup-Blocks into development