Merge latest from upstream - #3

…ension

Fix #162

Accepts files whose extension is not .docx or which does not have extension

…ih access to MatchData with regex capture groups etc

I needed to do a `substitute` where the match arg was a regex, and if it were gsub I'd be using a block to have access to capture groups in $1 $2 $3 etc. Because of the weird way variables $1 $2 $3 are handled in ruby and block scope, I couldn't provide a delegated block to give exactly the same API as ordinary gsub. My original idea was to do that, added on to existing #substitute.

But instead, had to provide a new/alternate #substitute_with_block method, with a block that actually gets a MatchData object as arg, and can access whatever it needs from there, including capture groups and match string.

Update README.md

Allow rubyzip 3.x as well as 2.x in gemspec

Add substitute_with_block method to TextRun, that can take a block wtih access to MatchData with regex capture groups etc

Update Ruby versions on CI