Issue 3289: substitute warnings for print statements
change print to warning. missing import statement
Merge remote-tracking branch 'upstream/master'
fixed warnings statements in pretty_symbology.py
Fix issue #879: series of undefined functions.
Issue 879: add test for series of a subclass of Function.

Now we can use also

    >>> class TestF(Function):
    ...     pass
    >>> TestF(x).series(x)
Issue 879: fix python3 failure.
lxml instead of libxml2 for c2p, google app engine supports lxml and generally better supported
empty line made quality test fail
apply_xsl real doctest instead of just usage example
doctest_depends_on added, doctest corrected
Addition of hypertangent and exponential cases to parametric differntial equations

 added code exponential for to special denom

added code for tangent cases to special denom

added code for tangent cases to special denom

First attempt to solve the section 5.12

first attempt to solve section 5.12 and related problems

First Attempt to implement section 5.12 and related problems

added hypertangent test cases for param special

deleted binary file
tested from within vim line-by-line over more files and missed import line in this file
3128: Sum/Product Simplification.
Simplification now hooked to simplify.
A bug fixed. Tests updated.
Tests updated.
Code quality improved.
Merge conflicts fixed.
Test failures fixed.