Conditional Keep Inventory

UPDATE TO Beta 0.2.6 (aka Beta0.2)

### Main changes

 * Made JsonArgumentType
 * Added ListComparator for command list identification
 * Added JSON Parse option to ConfigElem
 * Added config methods to get available ids for the command
 * Added use of command to append to lists

### Minor changes

 * edited the gitignore to ignore html files
 * edited README.md
 * edited config file writer (hoped a better JSON String parsing)
 * added folder creating log to the backup method
 * added Fabric API dependence, instead of just crashing the game
 * moved gamerules to the PLAYERS category

### **TODO:**

[✓] Player death Mixins altering drop
  ✓ Check if mod activated
  ✓ Check if keepInventory (vanilla) is true
   ✓ Check if death correspond to the wanted list
   ✓ Check if doVanishingCurse is activated
   ✓ Apply or not Curse of Vanishing if activated
[ ] Usage of config file
   ✓ Creating config file on read if missing
   ✓ Creating config file backup and a new one if error on read
   • Make backup name organised by number
   • Allow restoring backup from number
   • Make restoring able to backup actual config file
   ✓ Reading file on server startup and generate config data
   ✓ Change config data to save gamerules change before stop
   ✓ Save config on server stop
[ ] Use commands to alter config data
   ✓ Create the command
   x Create CDIActionArgumentType for first argument (no)
  ✓ Create CDIListArgumentType for command list selection
   ✓ Create JsonArgumentType for command editing config data
   ✓ Use command to add conditions
   • Implement config more data edition from command
  ✓ Add command alias for easier use
[ ] Pure development (post-beta?)
   • Add documentations to (as much as possible) all classes
[ ] And a few tests, as well...