Support dumping without indentation and newlines

Passing "indent=False" to wcfg.dump() or wcfg.dumps() will dump
values in a single line, minimizing used space by removing newline
characters and indentation. Some ancillary spaces are still around,
as well as trailing commas in arrays, nevertheless the output can
be much more compact and will fit in a single line -- as long as
string values do not have embedded newlines!