Can now load/save inventory!

Save is in ./data/players/$NAME/inventory.dat
Fix a TON of casting overflows

Should fix a lot of bugs, like high NetviewIds not working, or packets
not being acknowledged after some time, items not being sent correctly
(green apples bug!), etc..
Update .gitignore

Stop syncing my own save on GitHub.
Enable sayIcon for QuestScript, fix NPC bug

Enable sayIcon QuestScript command
Fix bug : All NPCs use the ID 0, *not* a unique ID.
Fix NPC bug

Fix the commands sometime being blocked after talking to a NPC (a
workaround was to open the menu).
Implement QuestScript 'give' command
Implement QuestScript 'setQuestState' commands
Implement QuestState 'giveBits' command
Implement QuestScript 'hasItem' commands
Implement QuestScript 'hasBits' command

Also fix some QuestScript bugs
Implement QuestScript 'jumpIfState' command