Move all floats to doubles

The code was developed initially around a pid loop implemented using
floats.  Therefore, the code was converting back and forth between
double for sensor values as inputs and outputs from this PID loop.

Change-Id: I2d2919e1165103040729c9f16bb84fde3dd6b81b
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/pid/fancontroller.hpp b/pid/fancontroller.hpp
index 821c900..f3d3f4e 100644
--- a/pid/fancontroller.hpp
+++ b/pid/fancontroller.hpp
@@ -28,9 +28,9 @@
     {
     }
 
-    float inputProc(void) override;
-    float setptProc(void) override;
-    void outputProc(float value) override;
+    double inputProc(void) override;
+    double setptProc(void) override;
+    void outputProc(double value) override;
 
     FanSpeedDirection getFanDirection(void) const
     {