Font tag in richtext

The richtext widget uses the <font/> tag to store the different font sizes selected by the user.

The problem is that this tag is not supported in HTML5 and we’re facing some problemes using it with weasyprint as the tag is simply ignored.

We’re going to solve this by replacing the tag with something that weasyprint understands but I wonder if the long term goal should be that Tryton stops using it.

Opinions?

It should not be hard to replace font tag with style attributes.

IIRC the style is already supported on older HTML versions, so if the generated tag is compatible with both versions this will be a good improvement.