More LGTM fixups (#1457)

* exclude lib dirs, fix 3 cpp errors

* fix more alerts, exclude mkvparse

Co-authored-by: George Hotz <geohot@gmail.com>
old-commit-hash: e568d3cadc

tools/replay/rqplot.py

@@ -1,12 +1,10 @@
 #!/usr/bin/env python
-import os
 import sys
 import matplotlib.pyplot as plt
 import numpy as np
 import cereal.messaging as messaging
 import time
 
-
 # tool to plot one or more signals live. Call ex:
 #./rqplot.py log.carState.vEgo log.carState.aEgo