Implement pre-context
string_group replaces eol with space. Need to decide what to do with the last line
Print the color after each \n char to ensure compatibility with less -R option
Divide regex to get eol char, spacing, content
Create method to merge match array results

- Use it in multi line matching
- Update regex for better multiline matching support
Fix tests, no_match ends with end of line to ease merging
perltidy
Bug fix: don't print precontext when not needed
Add placeholder for git-check-ignore
Put common code in a function
Add preprocessor-options option