Support Arguments values starting with non-word chars

[montgomerybc]

Updated regex to allow for non-word starting characters

[jpdillingham]

Closes #54

[jpdillingham]

Thanks for this, I agree it is a necessary change. When testing I uncovered a semi-related bug with paths starting with / instead of \; there's an explicit part of the regex that allows this with \\/? prior to the previous \w and it causes issues parsing something like /a /b /c into 3 bools, so I'll need to follow up with a PR to remove that.

I'm bringing this up because this is a breaking change and a reversal of slash support in values; previously --foo /bar.txt was supported and --foo \bar.txt was not; now the inverse will be true. Any values starting with a forward slash will need to be quoted.

Thanks again!