Clean up deprecated code and fix multiple issues

- Remove deprecated markdown_preview plugin and re-wrote
- Renamed alt_provider.py under words completer
- Fix words completion provider logic and cache handling
- Fix container orientations (VERTICAL -> HORIZONTAL) and add Separators
- Remove unused Gtk imports from search_replace plugin
- Fix event creation parameter order in source_file.py
- Fix typo in source_view.py (_load_pretify_json -> _load_prettify_json)
- Refactor webkit_ui with new load methods and enhanced settings

plugins/code/completers/words_completer/provider.py

@@ -18,7 +18,7 @@ class Provider(GObject.GObject, GtkSource.CompletionProvider):
         This is a Words Completion Provider.
         # NOTE: used information from here --> https://warroom.rsmus.com/do-that-auto-complete/
     """
-    # __gtype_name__ = 'WordsCompletionProvider'
+    __gtype_name__ = 'WordsCompletionProvider'
 
     def __init__(self):
         super(Provider, self).__init__()
@@ -37,6 +37,16 @@ class Provider(GObject.GObject, GtkSource.CompletionProvider):
 
         word = self.response_cache.get_word(context)
         if not word or len(word) < 2: return False
+
+        iter = self.response_cache.get_iter_correctly(context)
+        iter.backward_char()
+        ch = iter.get_char()
+        # NOTE: Look to re-add or apply supprting logic to use spaces
+        # As is it slows down the editor in certain contexts...
+        # if not (ch in ('_', '.', ' ') or ch.isalnum()):
+        if not (ch in ('_', '.') or ch.isalnum()):
+            return False
+
         return True
 
     def do_get_priority(self):