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/stepwisecontroller.hpp b/pid/stepwisecontroller.hpp
index 37606c3..4aa8116 100644
--- a/pid/stepwisecontroller.hpp
+++ b/pid/stepwisecontroller.hpp
@@ -26,9 +26,9 @@
     {
     }
 
-    float inputProc(void) override;
+    double inputProc(void) override;
 
-    void outputProc(float value) override;
+    void outputProc(double value) override;
 
     void process(void) override;
 
@@ -50,6 +50,6 @@
     ec::StepwiseInfo _stepwise_info;
     std::string _id;
     std::vector<std::string> _inputs;
-    float lastInput = std::numeric_limits<float>::quiet_NaN();
-    float lastOutput = std::numeric_limits<float>::quiet_NaN();
+    double lastInput = std::numeric_limits<double>::quiet_NaN();
+    double lastOutput = std::numeric_limits<double>::quiet_NaN();
 };