Auto fetch db tables & general improvements

Added :

• Tables fetch from db method (use sqlite_master data) with override parameter
• Automatic tables fetch on DBHandler creation
• Auto update Table sql query on object modification
• Generated equals and hashCode methods for db classes (Table, Column and Data)

Changed :

• DBHandler addTable method will now replace Table instance in tables array if it already exist

Fixed :

• Import issue when DBHandler tables array is empty (tables is now automatically refreshed on DBHandler creation with sqlite_master data)
• String concatenation bug in Table and Column classes (replaced += by concat() )

Importer implementation

Added :

• DBImporter abstract class for handle restore and import data from file to db
• DBImporterJson implementation for json import
• Import methods to DBHandler (restore/import ones, with or without custom file location)
• Alternative method in DBHandler for add Set of Data in db
• DbInteractionConfig abstract class
• ImportConfig class
• Ability to add excluded fields to import/export configs
• IOException handling in DBImporter
• Random code comments and debug logs
• Very basic use exemple in App

Fixed :

• Little fix in access modifiers for Abstract class constructors
• Lot of little and random issues / improvements

Known bugs :

• Import don't work if DBHandler instance tables array is empty or don't have updated list of existing tables
  -> Coming solution : fetch tables from db in constructor and update tables list