Update NTL to version 6.2.0.
Let FLINT build against NTL 6.2.
Update FLINT patch revision.
Fix some template issue with NTL 6.2.0.
Update NTL to version 6.2.1.
Fix checksum for NTL.
Include dot in extension for graphics_filename().

This makes the function more similar to tmp_filename(), so people may
have less trouble remembering where to include the dot and where not to.
This also enables the use of suffixes which don't start in a dot, like
those starting in a dash which are used by Graphics3d.show().

The old behaviour is deprecated but kept, at least for extensions starting
in neither a dot nor a dash.  That compatibility code may be removed a year
after this change here got released.
Generate names for 3d graphics files independently.

Instead of basing everything on a single call to graphics_filename,
we now have one call for (almost) every file which is being generated.
This ensures that the files with the corresponding extensions are indeed new.
Up until now, creating multiple 3d results in a single cell would likely
lead to clashes.
Gessel-Reutenauer symmetric functions
Carlitz-Shareshian-Wachs symmetric functions
dendriform smaller and smaller-or-equal operations on QSym
trivial optimization
expanding noncommutative symmetric functions in free algebra
decorativa
Refreshing patches and new configure.ac to generate a libtool that supports c++ properly.
Correct patch and change ordering between libtool generation and patching in spkg-install
documentation fixes
Reseparate make.patch properly from the libtool patch
ZZ instead of IntegerRing()
Merge remote-tracking branch 'origin/develop' into ticket/16640