Work done Up to 19/8

SQL Generation
The SQL Generator has been extended to handle the followings:
1. Multiple conditions can be processed by separating the logical operator (and/or) and breaking them into sub-queries which will be processed separately and combined into a single set of results.
2. Retrieve data from archive database.
3. Able to distinguish between categorical/numerical entities and handle them correspondingly.

User Interface
The user interface has been extended to allow:
1. Selecting patients by demographical information and historical information.

Other Features
The following statistical functions can now be included in CDAL:
1. mean
2. sd (standard deviation)
3. median
4. max (maximum)
5. min (minimum)