extrang: extract specific structures from .ang files

Usage:

extrang file_with_many_structs.ang num1 [num2 ...]

Description:

extrang takes a DIANA .ang file with multiple structures in it and extracts the specified structures. This may be obsolete now that DYANA can sort structures by penalty and save only the best ones.

Example:

extrang test.ang 012 014 009
will pull out the 9th 12th and 14th angle files from test.ang and save them as test009.ang, test012.ang and test014.ang.