Add support for leading spaces in search pattern

[sanderr]

Leading spaces are currently trimmed from the search pattern. I believe this is inherent in the library used to parse the config file. Since this effectively makes bumpversion unusable for any projects that need a search pattern with leading spaces, I think it would be valuable to add space (and potentially tab) to the special character context so it can be used similarly to {#}.

[florisla]

I think this makes sense. Where did you find out about {#}? I was not familiar with that.

[sanderr]

I found out about it by digging into the code when I was trying to find out the strange behavior that resulted in #198. See here.

[florisla]

We should document this in the README too.

What keywords do we use for space and tab? Simply {space} and {tab}?

[sanderr]

I agree documenting this would be a good idea. I believe there were some other things I didn't find in the README but I didn't think to write them down. I'll create another ticket if it comes to mind.

I like {space} and {tab}, I think they clearly convey the intention.

[jaap3]

I was trying to achieve the same thing. I'm using bumpversion to bump the version in a package(-lock).json and both the search and replace patterns need to be prefixed by two spaces (and include newlines). Limited (and undocumented) special character handling was added in PR #135, it would be nice if this was expanded to include whitespace characters.

[hukkin]

I think just like #221 this would most conveniently be fixed by allowing configuration in a .bumpversion.toml file, as TOML allows strings with leading and trailing whitespace.

[florisla]

TOML support is discussed in #42. But I think this approach is simpler, and thus could end up being release sooner too.

[kdeldycke]

This issue has been solved by bump-my-version thanks to its transition to TOML-based configuration files.