Fix layouts containing empty keys

This results in a key being the empty string and do not trigger an
error:

    key1="\"

Layouts are fixed and check_layout now checks for this case.

check_layout.output

@@ -39,7 +39,7 @@ Layout includes some ASCII punctuation but not all, missing: #, $, %, &, ', (, )
 Layout doesn't define some important keys, missing: esc, f11_placeholder, f12_placeholder, tab
 2 warnings
 # deva_inscript
-Duplicate keys: , ।
+Duplicate keys: ।
 Layout includes some ASCII punctuation but not all, missing: ", $, ', ^, _, `, |
 Layout doesn't define some important keys, missing: f11_placeholder, f12_placeholder
 3 warnings
@@ -95,8 +95,7 @@ Layout doesn't define some important keys, missing: f11_placeholder, f12_placeho
 # latn_qwerty_us
 0 warnings
 # latn_qwerty_vi
-Layout includes some ASCII punctuation but not all, missing: \
-1 warnings
+0 warnings
 # latn_qwertz
 0 warnings
 # latn_qwertz_cz
@@ -113,7 +112,7 @@ Layout doesn't define some important keys, missing: f11_placeholder, f12_placeho
 # latn_qwertz_hu
 0 warnings
 # latn_qwertz_sk
-Layout includes some ASCII punctuation but not all, missing: \, `
+Layout includes some ASCII punctuation but not all, missing: `
 Layout doesn't define some important keys, missing: f11_placeholder, f12_placeholder
 2 warnings
 # urdu_phonetic_ur

check_layout.py

@@ -66,6 +66,7 @@ def check_layout(layout):
                     [ "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9",
                      "f10", "f11", "f12" ],
                     "Layout contains function keys")
+    unexpected_keys(keys, [""], "Layout contains empty strings")
 
     bottom_row_keys = [
             "ctrl", "fn", "switch_numeric", "change_method", "switch_emoji",

res/xml/deva_inscript.xml

@@ -28,8 +28,8 @@
     <key shift="0.1" key0="ट" key1="ठ" key2="ड़" key3="\#" key4="*"/>
     <key key0="ं" key1="ँ" key2="।" key3="ॐ" key4="\@"/>
     <key key0="म" key1="ण" key2="य" key3="य़" key4="%"/>
-    <key key0="न" key1="" key2="।" key3=":" key4="&amp;"/>
-    <key key0="व" key1="" key2="ढ़" key3=";" key4="."/>
+    <key key0="न" key2="।" key3=":" key4="&amp;"/>
+    <key key0="व" key2="ढ़" key3=";" key4="."/>
     <key key0="ल" key1="ळ" key2="फ़" key3="!" key4=","/>
     <key key0="स" key1="श" key2="ष" key3="\?" key4="।"/>
     <key shift="0.1" width="1.4" key0="backspace" key2="delete"/>

res/xml/latn_qwerty_vi.xml

@@ -22,7 +22,7 @@
     <key key0="h" key2="=" key3="+"/>
     <key key0="j" key1="accent_dot_below" key3="{" key4="}"/>
     <key key0="k" key3="[" key4="]"/>
-    <key key0="l" key2="|" key3="\"/>
+    <key key0="l" key2="|" key3="\\"/>
   </row>
   <row>
     <key width="1.5" key0="shift" key2="loc capslock"/>

res/xml/latn_qwertz_sk.xml

@@ -10,7 +10,7 @@
     <key key0="u" key1="7" key2="ü" key3="ú" key4="ů"/>
     <key key0="i" key1="8" key3="í"/>
     <key key0="o" key1="9" key2="ö" key3="ó" key4="ô"/>
-    <key key0="p" key1="0" key2="=" key3="\" key4="/"/>
+    <key key0="p" key1="0" key2="=" key3="\\" key4="/"/>
   </row>
   <row>
     <key key0="a" key1="tab" key3="á" key4="ä"/>