Squashing per prior practice.  Commit log headers below.

* Updated S3 example

* Simpler stats dump use

* New utility function makeNanotime

* New domain getter helper functions

* Condition one more function on TileDB 2.0.0

* Manual pages updated from updated roxygen

* Add makeInteger64 helper

* Updates to empty domain getters

* Add Depends: on nanotime

* Updated print.tiledb_metadata documentation

* Comment-out tiledb/ci-r which does not have nanotime

* Generalized var char buffer getter

* Minor robustification for single logical expression test

* Ensuring tests pasts under R 4.0.0

* More roxygen changes for S4 method

Not entirely clear what drives them though

* Two R 4.0.0 corrections for 'not single logical'

* Park one test, minor update to cleanup

* Standardized function names

* Updated function

* Updated tiledb_array function with arg selections

* Add domain cell_var_num getter

* Snapshot with dynamic result creation

* Condition Dimension cell_val_num on having version 2.0.0

* Documentation update for tiledb_attr for ncells=NA

* Fix show when attrs is not empty (#114)

* Update src/Makevars, remove redundant C++11 decl from DESCRIPTION

* Updated and cleaned code comments

* Adding ggtags file to .gitignore

* Do not include ggtags file in package

* Remove flag from src/Makevars.in

* Modified ex_1 to more explicitly show double values

* Another roxygen back and forth

* Generalize quickstart_sparse

* Support two more types in one function

* Snapshot

* Updates to tiledb_array

* Remove one constraint, correct return

* Two approaches to issue 111

* Update NEWS.md

* Two updates from PR review

Co-authored-by: Aaron Wolen <aaron@wolen.com>