doc: mentions some helper functions provided by model

Also clean up the introduction text of the basic model doc.
driver simsem: fix not generating an data with shape == .resolution

With non integer values of scale, it could go completely wrong.
Now we compute much more precisely which pixel is "scanned".
util: new convertToObject() function

Converts a string to an object.
Like reproduceTypedValue but uses only the (YAML) syntax to guess the type.

Also update the CLI to make use of it.

Allows to set float when we want floats!
odemisd: clean up

use new Python syntax
tiff: add comment