Use more appropriate prefix for autocomletions

As autocompletion prefix, it is much more reliable to use the piece
of text from the beginning of the line until current text cursor,
rather than beginning and end of current line.

Author: tkopets

SQLTools.py

@@ -245,9 +245,12 @@ def on_query_completions(view, prefix, locations):
         completions = view.extract_completions(prefix)
 
         if prefix == "":
-            region = sublime.Region(locations[0], locations[0])
+            currentPoint = locations[0]
+            lineStartPoint = view.line(currentPoint).begin()
+            lineStartToLocation = sublime.Region(lineStartPoint, currentPoint)
             try:
-                prefix = view.substr(view.line(region)).split(" ").pop()
+                # everything after last space is a prefix
+                prefix = view.substr(lineStartToLocation).split(" ").pop()
             except Exception:
                 pass