Add a driver for the new IMU

Redo how zeroing works for the old one too.

This also forced me to update the ahal SPI library to a slightly pared
down version of what WPILib master has.

Change-Id: I631ff230c053c6256325ab6f4e532ca90c901424
diff --git a/y2019/BUILD b/y2019/BUILD
index d9cd4fd..328c93f 100644
--- a/y2019/BUILD
+++ b/y2019/BUILD
@@ -52,6 +52,8 @@
     srcs = [
         "wpilib_interface.cc",
     ],
+    # This library uses some deprecated parts of the SPI API.
+    copts = ["-Wno-deprecated-declarations"],
     restricted_to = ["//tools:roborio"],
     deps = [
         ":camera_log_fbs",