Subscription implemented
Continuous Query implemented
Fixed bugs when dealing with null values retrieved from tables
Removed unused code
Added basic performance test code

Bug fix

removed broken code

Docs
- Docs updated
  - include third party connectors links
  - local docs updated to web versions and fixed for compatability
Node
- Async added
- Deleted uncessary code
- Docs updated

1. code like `char msg[] = "xxxxxx"` unnecessarily copied the string to stack, changed to `const char* msg = "xxxxxx"`.
2. the 2rd argument of `setErrMsg` is changed from `char*` to `const char*`.
3. the 3rd argument of `setErrMsg` is removed as `strncpy` stops copying at the end of source string.

Implemented higher level API to make it more modular
Using promises and callbacks
Argument binding is now available e.g query(select ? from ?).bind("*", "table")

- Using _ to indicate variable/function is private and shouldn't be accessed
- Added JSDocs syntax to generate documentation
-