Set multiprocessCompatible to true, although this support is incomple…

…te, and this may lead to some errors.

https://developer.mozilla.org/en-US/Add-ons/Install_Manifests#multiprocessCompatible
https://github.com/yfdyh000/tabutils/issues?q=is%3Aopen+is%3Aissue+milestone%3Ae10s

install.rdf

@@ -4,7 +4,7 @@
     <em:id>[email protected]</em:id>
     <em:type>2</em:type>
     <em:name>Tab Utilities Fixed</em:name>
-    <em:version>1.5.2017.02.04</em:version>
+    <em:version>1.5.2017.08.17</em:version>
     <em:creator>YFdyh000</em:creator>
     <em:contributor>ithinc (Former author)</em:contributor>
     <em:contributor>Phil Tsarik</em:contributor>
@@ -32,5 +32,6 @@
       </Description>
     </em:targetApplication>
     <em:strictCompatibility>false</em:strictCompatibility>
+    <em:multiprocessCompatible>true</em:multiprocessCompatible>
   </Description>
 </RDF>