Minor bug fixes, and new functionality

Changelog:

Security

• security base class secured post function (_) updated with mysqli_real_escape_string function

Database

• added database set_encoding function
• added limit function
• added new function append()

Navigation

• added support for older apache version

Language class

• minor fix to the data retrieval function

Upload class

• minor bug fix for file upload extension detection

Other

• CKEditor removed due to a legal issue (you may download it manually)