Development build of v1.20. Add new features.

- Added dynamic versioning. Microweb will query the git repo to see if it's
  the latest version, and will show result on admin page.
- All inline HTML / PHP is now single lines, not preserving a max 74-char
  line length limit. While ugly, it generates smaller HTML files.
- Added page names to every admin page.
- Error page now redirects instead of showing the error page. This fixes an
  inifinite caching bug for requested pages which don't actually exist.
- Added option to replace a file when uploading.
- Hid cache files from pages list.
- Added link in admin interface to delete cache files.
- Passwords are now sha1 hashes. THIS WILL BREAK UPGRADES.