Foliantcontrib.escapecode

- fix: the bug of incorrect selection of the frontmatter has been fixed

- feat: frontmatter processing and option for frontmatter escaping

- feat: using Marko parser to identify pre blocks, fence blocks and inline code as well as comments
- feat: override pattern option in config

- Addition to normalization: remove BOM.

- Do not fail the preprocessor if saved code is not found, show warning message instead.

- Improve flexibility: add new actions, allow to override defaults.