Improvements mostly from jnxxx

[tbarnekov]

I've taken the liberty of merging the improvements from @jnxxx (previously attempted in PR #30). I believe I've fixed all the conflicts and also a few minor issues.

I've blatantly stolen most of the original description from #30

Overall changes are as follows:

Reading and writing setpoints using: manual_mode_fast, at_home_setting, leaving_home_setting, pause_setting, holiday_setting depending on the preset mode, rather than using temp_set as before.
It seems to work, so far.

Holiday preset modes added (home and away).

Quicker reaction to changes performed in the UI

Added floor temperature sensor

Fix for setmode issue

Added action and service call to set target temperature for a specific preset mode.
Preset mode is optional, and writes to current preset mode when not specified.

Added an indication for 'banner control' (local override).
When setpoint is changed locally from the thermostat it raises this flag and uses this as manual target setpoint.

[MTrab]

Thank you :)