A tokenizer for LaTeX. \GetTokens{Target1}{Target2}{Source}
splits source into two tokens at the first encounter of a
comma. The first token is saved in a newly created command with
the name passed as <Target1> and the second token likewise. A
package option 'trim' causes leading and trailing space to be
removed from each token; with this option, the \TrimSpaces
command is defined, which removes leading and trailing spaces
from its argument.
