Added *.~dsk files to gitignore
More support for user-defined functions ("lambdas")

Added LambdaParameter class, to represent parameters to lambdas.

Func1/Func2 now takes a lambda as body.

Added sqr() and sin() functions, where sin will be a built-in.
Started on OpenCL support

Writing a custom wrapper, using the ported OpenCL headers from
delphi-opencl[1] project (BSD license). The cl units have been modified
slightly.

[1]: https://code.google.com/p/delphi-opencl/
Added attribution of delphi-opencl project in readme