Editing EDF item effects and inventory/Weapons-branch

'''REMOVE THIS WARNING AT A LATER DATE: Much of this page is in-development features, from inventory-branch-2016, and its successor weapons-branch. This exists solely for the purpose of easily moving this article back over when weapons-branch is to be merged back into master, and should under no circumstances be used as a reference.'''

Define what happens when an item is picked up (and eventually, used or dropped from the inventory - this is not complete yet).

There are many different types of item effect definitions:
===artifact===
An artifact is an item which, when collected, goes into the player's inventory.

 artifact <name>
 {
  amount         <int> // amount gained with one pickup
  maxamount      <int> // max amount that can be carried in inventory
  interhubamount <int> // max amount carryable between levels in different hubs;
                       // -1 if this field should not apply at all
  sortorder      <int> // key used for sorting the player's inventory
  icon           <str> // name of icon graphic for invbar (currently unused)
  usesound       <str> // sound made when item is used (currently unused)
  useeffect      <str> // name of item effect to use for activation (unused)
  
  [+-]undroppable      // if +, cannot be dropped from inventory
  [+-]invbar           // if +, appears in invbar; otherwise, invisible
  [+-]keepdepleted     // if +, will remain in inventory with amount of zero
  [+-]fullamountonly   // if +, cannot pickup unless full amount is needed
  
  // artifacttype determines what sort of artifact this is.  
  artifacttype   <str> // "Normal", "Ammo", "Key", "Puzzle", "Power", "Weapon",
                       // or "Quest"
                       
  // The following fields apply only to certain artifact types. They have no
  // effect if specified on other types.
  
  // Ammo
  ammo.backpackamount    <int> // amount of this ammo type given by a Backpack
  ammo.backpackmaxamount <int> // max amount after collecting a Backpack
 }
===healtheffect===
A health effect gives the player health in one of many possible ways. 
 healtheffect <name>
 {
  amount     <int> // amount of health to give
  maxamount  <int> // max amount this item can health to; if player has greater
                   // health, the item cannot be picked up at all.
  lowmessage <str> // alternate message to give instead of pickupfx message when
                   // health is < amount; if starts with $, is a BEX mnemonic.
  
  [+-]alwayspickup  // if +, item is picked up even when unneeded (ie Health Bonus)
  [+-]sethealth     // if +, item SETS health rather than adding to it (ie Megasphere)
 }
===armoreffect===
An armor effect defines the properties of player armor 
 armoreffect <name>
 {
  saveamount    <int> // amount of armor given
  savefactor    <int> // numerator of fraction determining save percentage
  savedivisor   <int> // denominator of fraction determining save percentage
  maxsaveamount <int> // max amount his item can give; if player has greater
                      // armor, the item cannot be picked up at all
                      
  [+-]alwayspickup    // item is picked up even when unneeded (ie Armor Bonus)
  [+-]bonus           // if +, is a bonus (adds to current armor type without
                      // changing the protective qualities)
 }
===ammoeffect===
Ammo givers give an Ammo type artifact to the player.
 ammoeffect <name>
 {
  ammo       <str> // Name of an Ammo-type artifact definition
  amount     <int> // Amount to give for an ordinary pickup
  dropamount <int> // Amount to give if dropped by an enemy
  
  [+-]ignoreskill  // if +, does not double on skills that give double ammo  
 }
===powereffect===
Power givers give a power to the player.
 powereffect <name>
 {
  duration   <int>  // Length of time to last in tics
  type       <str>  // Name of power to give
  
  [+-]additivetime  // if +, adds to current duration
  [+-]permanent     // if +, lasts forever  
  [+-]overridesself // if +, getting the power again while still under its influence is allowed
 }
===weapongiver===
Weapon givers give a Weapon type artifact to the player, and optionally any number of Ammo artifact types.
 weapongiver <name>
 {
  weapon     <str> // Name of a weaponinfo to give to the player  
  ammogiven  <ammo>, <amount> [, <dropammount> [, <dmammount> [, <coopweaponsstay>]]] // Ammo type artifact given, and the amounts
                                                                                      // given based on how it was picked up. If the
                                                                                      // last three are left blank, only "amount" is used.
 }