Made library twig a dependency

Provides a template engine.
Started using templates
Added template installer
Introduced functions to render errors and notices
Extracted functions from installer
Do not put tabs in config file
Output a complete html document when config.php exists
Made installer use templates
Check the code style of all files in install/
Cleaned up indention of initial php code
Use a template for fatal errors
Started working on a template for the main site
Cleaned up installer functions
Config has no closing tag any more
Continued working on main template
Changed base of twig's loader
Added macros for tags and messages
Preparing main file for template usage
Changed title of main template
Added all variables needed by the header (main page)