remove deprecated prec arguments

[rws]

There are still three instances of the prec keyword argument:

src/sage/functions/other.py:            deprecation(7490, "The prec keyword argument is deprecated. Explicitly set the precision of the input, for example gamma(RealField(300)(1)), or use the prec argument to .n() for exact inputs, e.g., gamma(1).n(300), instead.")
src/sage/functions/other.py:            deprecation(7490, "Calling symbolic functions with arguments that cannot be coerced into symbolic expressions is deprecated.")
src/sage/functions/log.py:            deprecation(7490, "The prec keyword argument is deprecated. Explicitly set the precision of the input, for example exp(RealField(300)(1)), or use the prec argument to .n() for exact inputs, e.g., exp(1).n(300), instead.")

[jdemeyer]

Did you check that the documentation builds properly? This looks bad (double colon but block removed):

TESTS::

- sage: exp(2,prec=100)
- doctest:...: DeprecationWarning: The prec keyword argument is deprecated. Explicitly set the precision of the input, for example exp(RealField(300)(1)), or use the prec argument to .n() for exact inputs, e.g., exp(1).n(300), instead.
- See http://trac.sagemath.org/7490 for details.
- 7.3890560989306502272304274606
-

[jdemeyer]

Please justify why you undo the deprecation of

sage: Q.<i> = NumberField(x^2+1)
sage: gamma(i)

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​0f57738	Merge remote-tracking branch 'origin/develop' into 16698
​ba38202	fix reviewer comments

[aapitzsch]

I removed TESTS::. BTW the documentation of this function is not shown in the html reference documentation.

Replying to jdemeyer:

Please justify why you undo the deprecation of

sage: Q.<i> = NumberField(x^2+1)
sage: gamma(i)

I misinterpreted the deprecation warning. Now an exception is raised.

[aapitzsch]

Has been removed in #16023.