Some icons are inconsistent between skins in PDA portal.

Definitions within pda.css are inconsistent.
1. Although the icons of the synoptic tools were defined to default-skin via SAK-20839, it is not done to neo-skins.
2. The icon of the synoptic chat tool is not defined.
3. Although JForum and Melete icons were corrected via SAK-21053, it is not done to the PDA portal.
4. Some icons added via SAK-20772 or SAK-21800 are missing in some skins.