floating point reading data

[huss]

Initially OED only read pulse meters that returned integer values. The current database stores these readings as int. As we expand devices, we need to accept floating point values. The database needs to be converted to do this. The hope is the changes to the code will be minimal. As part of this process we need to decide on the floating point datatype to use (32-bit vs 64-bit accuracy) and also migrate all current data to the new format.

[huss]

Once we begin accepting data from non-MAMAC sources, we need to have this feature to preserve the data values. We certainly need by release 1.0 but maybe sooner.

[huss]

I was looking at the code and noticed that src/server/migrations/0.3.0-0.5.0/sql/readings/set_reading_type_to_real.sql altered the reading table to be floating point. I have done very limited testing but floating point values do graph that way. Thus, this issue seems solved unless someone sees an issue in the future.