Remove italic font style for RegEx braces and brackets (#111)

During the transition from the old to the new theme API the font style
for RegEx braces and brackets were changed to "italic".
It looks way cleaner and less distracting without italic font style especially because it is mixed with normal styles.

Resolves GH-107

resources/themes/nord.xml

@@ -1541,13 +1541,11 @@
     <option name="REGEXP.BRACES">
       <value>
         <option name="FOREGROUND" value="ebcb8b" />
-        <option name="FONT_TYPE" value="2" />
       </value>
     </option>
     <option name="REGEXP.BRACKETS">
       <value>
-        <option name="FOREGROUND" value="e8bf6a" />
-        <option name="FONT_TYPE" value="2" />
+        <option name="FOREGROUND" value="ebcb8b" />
       </value>
     </option>
     <option name="REGEXP.CHAR_CLASS">