Converters: Added empty Converters module

The Converters module will contain modules that convert specific database types to other ones.
txt2sqlite: Added txt to sqlite database converter

Implemented this converter to convert plain text databases to sqlite databases.
ConvertCommand: Implemented command to convert database types

The convert command converts one database type into an other one. Currently only text to sqlite3 is implemented.
Main: Added convert command
Command: Edited usage to include the convert and help command

Edited the general usage information to include the help command and the new convert command.
CreateCommand: Added command specific usage

Edited the usage command to print command specific information.
ConvertCommand: Added command specific usage

Edited the usage command to print command specific information.
Main: Implemented command specific help

Implemented the help command to display the usage of a specific command if it is specified on the command line.
Command: Added optional parameter to help usage

The help command now accepts a command name to display command specific usage. This functionality is now added to the general usage.
README, man: Added optional parameter for the help command.
README, man: Added info for the convert command
README, man: Added database_type option for the configuration file