Added command to set a trekker's emblem stats

Usage:
`!e [character id] [slot id - this is between 1 and 3] [attr 1] [attr 2] [attr 3] [attr 4]`

Example:
`!e 141 1 1004 1004 1004 1004` = Sets the first emblem of the character to all +ignis damage.

Notes:
Attribute ids can be found in `CharGemAttrValue.json` in the resources/bin folder.

src/main/java/emu/nebula/game/character/CharacterGemPreset.java

@@ -27,7 +27,9 @@ public class CharacterGemPreset {
         return this.getGems().length;
     }
     
-    public int getGemIndex(int slotIndex) {
+    public int getGemIndex(int slotId) {
+        int slotIndex = slotId - 1;
+        
         if (slotIndex < 0 || slotIndex >= this.getLength()) {
             return -1;
         }