Added .gitignore file
Added .init and .verify commands to gpkg shell

Added .init and .verify commands to gpkg shell.
These commands create and verify the geopackage tables respectively.
Geopackage meta tables are no longer created upon launching the Shell
app.
Removed IntelliJ project files
Refactored meta command handling.

Refactored meta command handling.
Meta commands are executed using polymorphism rather than with a big
conditional block.