This patch is the first step towards implementing support for
interactive forms (AcroForms). It makes it possible to render text
widget annotations exactly like Adobe Reader/Acrobat.
Everything we implement for AcroForms is disabled by default using a
preference, mainly because it is not ready to use yet, but has to
implemented in many steps to avoid complexity. The preference allows us
to work with the code while not exposing the behavior by default. Mainly
storing entered values and printing them is still absent, which would be
minimal requirements for enabling this by default.
