check_assumptions(): handle only bool values.

Assumption dicts only have values in {True, False, None}, so
there is no reason to complicate the code by special-casing
anything else.
check_assumptions(): Don't use new-style assumptions.

There is no guaranteed correspondence between old and new
assumptions with the same name.
Fix RootOf assumptions.

Fixes issue 3551.
Update doc/README.rst
Update doc/Makefile

Use foreach instead of  a bash for loop, thus stopping on the first error.
tutorial: formatting only.
tutorial: Update link to extended installation instructions.
Update tutorial.pot
Update tutorial.??.po
Update tutorial.zh.po
Doc formatting.
Fix typo.
Make sure Sphinx extensions are put in the front of the PATH
Merge pull request #1691 from rlamy/real-solve

Fix issue 3551
Merge pull request #1693 from jrioux/documentation

Documentation

Update the link to extended installation instructions in the tutorial. Clean up the formatting of the doc a bit. Update the translations and make sure that make html reports failure on the first error encountered.
Merge pull request #1694 from asmeurer/sphinx_extensions

Make sure Sphinx extensions are put in the front of the PATH
modifications to trigsimp

* import functions at top rather than using C
* allow multiple pattern matches by iterating; I'm not
  sure if a loop is possible; if so, caching results and
  breaking if a previous result was seen could be done.
* added _dotrig helper to assess whether the expr
  and the pattern got together (hyperbolic patterns
  need not be used on non-hyperbolic expressions)
* the patterns are computed once in the helper function,
  _trigpatterns; changes there include:
  - a trig/hyperbolic-excluding Wild is used rather
    than running a test after the match
  - the "other identity" matchers were added so
    cos(b)**2 will simplify to 1 - sin(b)**2, for example
  - the sum/difference of angles formulas were added
  - the artifacts matchers are preprocessed once so
    the replacement of `a` with `a_t` doesn't have
    to be done every time
* _trigsimp strategies were modified:
  - factor_terms and separation of variables is used on the first pass
  - the non-trig/hyperbolic portions are removed from a Mul before
    processing
  - expand_mul rather than expand is used to look for a simpler Add
  - the repetition for applying the same artifact is
    only done once since it has a coefficient to allow multiple
    occurances to be removed in one pass; and trigsimp iterates
    now, so if something can happen again, it will.
  - factoring and rewriting are tried as a last resort on an Add
  - since Mul was already being handled in the main _trigsimp
    loop, it isn't re-traversed by the last elif-block (which now
    handles Pow and non-Expr objects)
* test from many issues were added and a simpler result noted which
  might be obtained if half angle formulas are implemented.

Fu needs to be implemented. This is a real oodle of code.
DEBUG trigsimp debug statements
try factoring and rewriting at end for Add, Mul; add more patterns
remove some hyperbolic patterns; check validity of pattern