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/builderconfig.cpp b/pid/builderconfig.cpp
index 665e2dd..f85e1c1 100644
--- a/pid/builderconfig.cpp
+++ b/pid/builderconfig.cpp
@@ -92,10 +92,10 @@
 
                 /*
                  * Mysteriously if you use lookupValue on these, and the type
-                 * is float.  It won't work right.
+                 * is double.  It won't work right.
                  *
                  * If the configuration file value doesn't look explicitly like
-                 * a float it won't let you assign it to one.
+                 * a double it won't let you assign it to one.
                  */
                 name = pid.lookup("name").c_str();
                 info.type = pid.lookup("type").c_str();