Major update to support HTML emails. Will now handle HTML text formatting, embedded images, hyperlinks, lists, etc.

Fix missing attachment field in options page, implement max email clip size, misc bug fixes

Added support for email attachments.
Various cleanup in source.

- Major refactor to centralize functionality into background.js to support future features.
- Added ability to clip selected text. (Issues 12 & 22 at github)
- Added ObsidianClipper to menu. (Issue 18 at github)
- Added status line messages.
- Various cleanup and bug fixes.

Added CC/BCC features and YAML support for same.

Changed colored tags to use CSS instead of broken HTML.

Added theses new features:
- Clickable email IDs - Add '[click here to open](_MSGURI)' to a template to click in Obsidian and open original email in Thunderbird.
- Message tags - Add '_MSGTAGSLIST' in your template to get a list of Thunderbird tags in color.
- Additional time/date fields - Use Year/month/date/hour/minute/second to format time any way you want.
- New character substitution options
- General cleanup and refactoring.

Improved ability of user to exclude or substitute characters in filenames.
Improved documentation.