Bug 894094 - Add .idea folder (created by JetBrains IDEs) to .hgignore. r=BenWa

.hgignore

@@ -47,6 +47,9 @@ _OPT\.OBJ/
 \.cproject$
 \.settings/
 
+# Ignore the directory that JetBrains IDEs create
+\.idea/
+
 # Python stuff installed at build time.
 ^python/psutil/.*\.so
 ^python/psutil/.*\.pyd