setpoint changes for better visualization

Created "upgrade_setpoints.php" to support this upgrade.  This file is
untested so proceed at your own risk (highly recommend db backup prior
to performing this upgrade).

Summary of changes:
1) Changed the 'thermostats' table 'id' column to a tinyint unsigned
type.
2) Added a new database table called setpoints with foreign key
reference to thermostats.id.
3) Dropped the 'temperatures'.'set_point' column as it's no longer
needed.
4) Modified the update status and temps scripts to manage the new
setpoints database table and remove the old method.
5) Modified the draw_daily.php to render as an overlay the new set_point
logic.  Also adjusted previous settings for pixel calculations of the
heat/cool/fan status's as I discovered they were slightly misaligned.
Added commentary with all changes.
6) Modified other support scripts where I found they could be updated
but I'm not sure all of them are still even being used.