rename ravenlog to krowlog

There is a database named RavenDB.
KrowLog starts with a K, which is a) distinctive and b) has an association to KDE.

src/ui/bigtext/highlight.py

@@ -0,0 +1,12 @@
+from typing import Optional, List
+
+from src.ui.bigtext.line import Line
+from src.ui.bigtext.highlighted_range import HighlightedRange
+
+
+class Highlight:
+    def __init__(self):
+        pass
+
+    def compute_highlight(self, line: Line) -> Optional[List[HighlightedRange]]:
+        return None