Improve zwnj/halfspace symbol and Persian layout (#711)

* Fix persian's half-space invisibility
* Add a 0.5 space before ظ in persian
* Change the place of چ in persian
* Change the width of backspace in persian
* Rename zwnj to halfspace in KeyValue.java and beng_provat layout

srcs/juloo.keyboard2/KeyValue.java

@@ -550,7 +550,8 @@ public final class KeyValue implements Comparable<KeyValue>
       case "meteg_placeholder": return placeholderKey(Placeholder.METEG);
       /* intending/preventing ligature - supported by many scripts*/
       case "zwj": return charKey("zwj", '\u200D', 0); // zero-width joiner (provides ligature)
-      case "zwnj": return charKey("zwnj", '\u200C', 0); // zero-width non joiner (prevents unintended ligature)
+      case "zwnj":
+      case "halfspace": return charKey("⸽", '\u200C', 0); // zero-width non joiner
 
       /* Editing keys */
       case "copy": return editingKey(0xE030, Editing.COPY);

srcs/layouts/arab_pc_ir.xml

@@ -11,7 +11,7 @@
     <key key0="ه" key2="۸" key3="*"/>
     <key key0="خ" key2="۹" key3="(" key4=")"/>
     <key key0="ح" key2="۰"/>
-    <key key0="ج"/>
+    <key key0="ج" key2="چ"/>
   </row>
   <row>
     <key key0="ش" key2="loc tab"/>
@@ -20,14 +20,14 @@
     <key key0="ب"/>
     <key key0="ل"/>
     <key key0="ا" key1="آ" key4="ء" key2="-" key3="_"/>
-    <key key0="ت" key1="&#x200C;" key2="+"/>
+    <key key0="ت" key1="halfspace" key2="+"/>
     <key key0="ن"/>
     <key key0="م"/>
     <key key0="ک"/>
     <key key0="گ"/>
   </row>
   <row>
-    <key key0="ظ"/>
+    <key shift="0.5" key0="ظ"/>
     <key key0="ط"/>
     <key key0="ز" key2="«"/>
     <key key0="ر" key2="»"/>
@@ -36,7 +36,6 @@
     <key key0="د" key2="؛"/>
     <key key0="پ" key2="&#1567;"/>
     <key key0="و"/>
-    <key key0="چ"/>
+    <key width="1.5" key0="backspace" key2="delete"/>
-    <key width="1.0" key0="backspace" key2="delete"/>
   </row>
 </keyboard>

srcs/layouts/beng_provat.xml

@@ -21,7 +21,7 @@
 		<key 				key0="হ"		key1="ঃ"		key2="="	key3="+"							/>
 		<key 				key0="জ"	key1="ঝ"				key3="ে"		key4="ৈ"					/>
 		<key 				key0="ক"	key1="খ"				key3="ো"	key4="ৌ"				/>
-		<key 				key0="ল"	key1="ং"		key2="॥"		key3="zwnj"							/>
+		<key 				key0="ল"	key1="ং"		key2="॥"		key3="halfspace"							/>
 	</row>
 	<row>
 		<key width="1.5"	key0="shift"															/>