Fix memory leak in qqbar.ANRoot._interval_fast()

sage.rings.qqbar.ANRoot._interval_fast() used to create new interval fields by
type(self._interval.parent())(prec), thus bypassing the cache provided by
RealIntervalField().
Doctest syntax
No longer use testjava.sh script
Remove testjava.sh from jmol package
make sure every codeword returned is immutable
#ticket → :trac:`ticket`
Trac #15493: qqbar.ANRoot creates tons of copies of interval fields

`sage.rings.qqbar.ANRoot._interval_fast()` creates new interval fields
by `type(self._interval.parent())(prec)`, thus bypassing the cache
provided by `RealIntervalField()`. Computations with algebraic numbers
sometimes need gigabytes of memory to store these parents and the
associated coercion structures.

Before (6.2.beta5):
{{{
sage: set_random_seed(42)
sage: m = get_memory_usage()
sage: %time l = list(QQbar.random_element(poly_degree=3) == 0 for i in
range(4000))
CPU times: user 10.7 s, sys: 24 ms, total: 10.7 s
Wall time: 10.7 s
sage: get_memory_usage(m)
7.77734375
}}}
With patch:
{{{
sage: set_random_seed(42)
sage: m = get_memory_usage()
sage: %time l = list(QQbar.random_element(poly_degree=3) == 0 for i in
range(4000))
CPU times: user 10.5 s, sys: 40 ms, total: 10.5 s
Wall time: 10.5 s
sage: get_memory_usage(m)
0.34375
}}}

URL: http://trac.sagemath.org/15493
Reported by: mmezzarobba
Ticket author(s): Marc Mezzarobba
Reviewer(s): Vincent Delecroix, Jeroen Demeyer
Trac #16469: some_code.random_element() does not return immutable elements

{{{
sage: C = codes.HammingCode(3,GF(2))
sage: c = C.random_element(); c
(0, 1, 1, 1, 1, 0, 0)
sage: c[0] = 1; c
(1, 1, 1, 1, 1, 0, 0)
}}}

URL: http://trac.sagemath.org/16469
Reported by: ppurka
Ticket author(s): Punarbasu Purkayastha
Reviewer(s): Nathann Cohen
Trac #14364: The jmol spkg contains testjava.sh

This script would be better in the sage-scripts spkg, as it's sage-
specific, probably as sage-testjava.sh or some such. The change will
break one doctest in devel/sage/sage/interfaces/jmoldata.py, where it is
looking for it using the full path.

URL: http://trac.sagemath.org/14364
Reported by: Snark
Ticket author(s): Steven Trogdon, Jeroen Demeyer
Reviewer(s): Snark