Added better error detection, ability to handle multiple formats for creds

- __construct uses try/catch, with several checks for throwing
- If file is a string, find its full path in include_path()
- Can be of types JSON, INI, or XML (defaults to ini if no extension).
- Use Exceptions instead of magic constants for line, allowing better
debugging
- Formatting fixes
Use 'connect.ini' instead of 'connect' for database default credentials
Store default credentials as a static variable

Default is ini
Use static var for all connection parsing extensions
$config is now public var as well. Required for use as credentials