Offer-motivated features: :hline defaults, ranged :hpos, @date :days, :bottom none

- @table: a writer's :hline/:vline replaces the default lines; new
  boundary name 'none' removes all lines
- @table: ranged :hpos argument overrides :cell_hpos per cell
  (\multicolumn{1} in tex; positions a colspan anchor's merged cell)
- @date/@datetime: :days offset argument (sks/date/date.py)
- @document: ":bottom none" suppresses the footer (\pagestyle{empty})

Also carries the escape-system generator/renderer fixes, per-cell-range
:format, and uppercase .TTF/.OTF font recognition from klammertext-dev.

sks/date/date.py

@@ -0,0 +1,17 @@
+# Implementation of the @date and @datetime klammers (date.k).  Each takes
+# the current date and time, offset by the :days argument (positive is
+# future, negative is past), and formats it.
+
+import datetime as dt
+
+
+def offset(days):
+    return dt.datetime.now() + dt.timedelta(days=days or 0)
+
+
+def date(K):
+    return offset(K.days).strftime("%d %B %Y").lstrip("0")
+
+
+def datetime(K):
+    return offset(K.days).strftime("%d %B %Y, %H:%M").lstrip("0")