Fix type bug in model.meta

isFinite([x]) is true if x is a number! which meant m.meta([n]) was
returning a singleton rather than a mappable type, which was crashing
cite_docs, which was crashing topic_view when there was just a single
doc in the year. Should be corrected.
delete some extra whitespace
view.topic.docs: messaging if no docs

Should only be able to reach this if you go directly to #/topic/year
where year is a year with no docs on topic. Still, let's try to catch
this and do something reasonable.
use .none for no-topics msg in view.word too
update minified source
validate year before invoking topic_docs

This fixes glitchy responses to #/topic// (since isFinite("") is true).

Also, switching from cacheing doc years on the main-thread model object
to just evaluating them as needed for topic_docs(, year). Doesn't look
like a serious performance problem. Instead, what's cached is a d3.set
of valid years, since we have that sitting around when we load metadata.
update minified source
default rather than floating navbar at top

This degrades a bit more gracefully on small screens.
right-align doc table td's, not just th's

also, doc_view header reads "tokens" to be consistent with
topic_view_docs
fix failure to set up word form in one case

i.e. when the first place the site loads is #/word/.

Also, eliminate some glitchy error messaging in the case when the
requested word gets no hits as in #/word/blorf.
fix glitched sort link on model list view

when you first enter the model at #/model/list/*/down, there would be
problems when you then tried to alter the sort order by clicking column
heads. Fixed the conditional for dealing with these edge cases.
Should work right now.
update minified source