ilmbase 2.5.7 Utility C++ libraries for threads, maths, and exceptions

IlmBase provides several utility libraries for C++. Half is a class that encapsulates ILM's 16-bit floating-point format. IlmThread is a thread abstraction. Imath implements 2D and 3D vectors, 3x3 and 4x4 matrices, quaternions and other useful 2D and 3D math functions. Iex is an exception-handling library.