srep performs bulk replacements on the contents of series of files.

It is driven by a data file with replacement instructions.

When processing the files, each file is rewritten when one or more of
the replacement instructions succeed. If no replacement instructions
succeed, the file is left unmodified.

All the power of Perl patters can be used in the replacement
instructions. Additionally, facilities are provided for easy
replacement of words and balanced bracketed strings.
