deprecation warnings in interacts.calculus.newton_method()

[slabbe]

On top of #22636, the following command

interacts.calculus.newton_method()

prints many deprecation warnings:

Precision 2h=0.001

/Users/slabbe/Applications/sage-git/local/lib/python2.7/site-packages/sage/interacts/library.py:909: DeprecationWarning:  html(...) will change soon to return HTML instead of printing it. Instead use pretty_print(html(...)) for strings or just pretty_print(...) for math. 
See http://trac.sagemath.org/18292 for details.
  html(r"$\text{Precision } 2h = %s$"%latex(float(h)))

c=1.4142141576301823

/Users/slabbe/Applications/sage-git/local/lib/python2.7/site-packages/sage/interacts/library.py:910: DeprecationWarning:  html(...) will change soon to return HTML instead of printing it. Instead use pretty_print(html(...)) for strings or just pretty_print(...) for math. 
See http://trac.sagemath.org/18292 for details.
  html(r"${c = }%s$"%c)

f(c)=1.6836416461×10−06

/Users/slabbe/Applications/sage-git/local/lib/python2.7/site-packages/sage/interacts/library.py:911: DeprecationWarning:  html(...) will change soon to return HTML instead of printing it. Instead use pretty_print(html(...)) for strings or just pretty_print(...) for math. 
See http://trac.sagemath.org/18292 for details.
  html(r"${f(c) = }%s"%latex(f(c)))

6 iterations

/Users/slabbe/Applications/sage-git/local/lib/python2.7/site-packages/sage/interacts/library.py:912: DeprecationWarning:  html(...) will change soon to return HTML instead of printing it. Instead use pretty_print(html(...)) for strings or just pretty_print(...) for math. 
See http://trac.sagemath.org/18292 for details.
  html(r"$%s \text{ iterations}"%len(midpoints))

[jdemeyer]

Duplicate of #22644