Change chp.regex to regex in all files

[jaxford]

build_html.pl fails to create html files with this error:

Unknown link regex

Replacing chp.regex with regex in these files corrects the problem:

sections/autoload.pod
sections/chapter_06.pod
sections/implicit_ideas.pod
sections/values.pod

[davorg]

I just came here to submit a very similar PR. I'm guessing that somewhere in the code, the link references are constructed using (\w+) in a regex. So chp.regex is created as regex and you get the error that @jaxford mentioned above (regex is the name of a missing link reference).

I fixed it by changing chp.regex to chp_regex - but this fix works just as well.

[sd43]

I should have seen this earlier. The problem is with the regex not being able to extract the complete link name as @davorg mention. I made a fix by using the start_L and end_L callbacks to get the position of the text having the link name.