1) Further styling tweaks for Dark Theme.

2) Theme related code changes are removed from config.py and moved to miscellaneous under a new package - "themes".

web/config.py

@@ -487,25 +487,6 @@ try:
 except ImportError:
     pass
 
-THEMES = {
-    "standard": {
-        "disp_name": "Standard",
-        "cssfile": "pgadmin",
-        "preview_img": "standard_preview.png"
-    }
-}
-
-OTHER_THEMES = {}
-try:
-    extra_themes = json.load(open('pgadmin.themes.json'))
-    OTHER_THEMES.update(extra_themes)
-except Exception:
-    pass
-
-# Set OTHER_THEMES to None here to disable all other themes
-
-if OTHER_THEMES is not None:
-    THEMES.update(OTHER_THEMES)
 
 # SUPPORT_SSH_TUNNEL can be override in local config file and if that
 # setting is False in local config then we should not check the Python version.