Market item filtering improvements and other some minor improvements

* Can now filter market items by vocation, level, slot type, and depot items.
* Added new bitwise lib for handling flag operations.
* Can now get/set local player vocation/premium (TODO: spell list).

modules/corelib/ui/uicombobox.lua

@@ -8,6 +8,12 @@ function UIComboBox.create()
   return combobox
 end
 
+function UIComboBox:clearOptions()
+  self.options = {}
+  self.currentIndex = -1
+  self:clearText()
+end
+
 function UIComboBox:setCurrentOption(text)
   if not self.options then return end
   for i,v in ipairs(self.options) do
@@ -29,6 +35,12 @@ function UIComboBox:setCurrentIndex(index)
   end
 end
 
+function UIComboBox:getCurrentOption()
+  if table.hasKey(self.options, self.currentIndex) then
+    return self.options[self.currentIndex]
+  end
+end
+
 function UIComboBox:addOption(text, data)
   table.insert(self.options, { text = text, data = data })
   local index = #self.options