A slight refactor to the RTE code; more abstraction and code into XMLFast.

Fix bug in xml/json/tab handling (from upstream change in what the "tab"
format argument does).

Also, unit tests from local staging of some of these operations.

Fixes #122.
new url for panther rte engine
bump
doc bump
bump
Text download reinstated for goose; at some point it went awol. Fixes #121.
lower scientific precision to %.3e; fixes #118.
text changes; fixes #116
new image for TE (and modable svg), clarify text so images do not seem
like links; fixes #119
doc bump
bump
new url for panther
convert \s input to simple \n separated input
fixes #115
Merge branch 'master' into 2.1.x