Escaping, table layout, and document fixes

Quoted Klammertext specials (^@ ^| ^# ^^ ^: ^*) and ^'...'^ regions now
survive re-processing (held as escape markers until final output);
:after_apply phase functions receive and return raw target text.

Tables: :hpos element position (center|left|right|<length>) replaces the
unimplemented :center/:indent; the ranged cell override is renamed
:justify; :column_width works in html (colgroup widths) and gains
'fill' -- the remaining width, capped at the column's widest entry, in
both targets; a table wider than the text column warns on the console;
table edges without an outer line set their text flush on the margins.

@document: no empty title bar for untitled documents; @vfill fills to
the bottom of the window in html (pure CSS); @vspace in plain text;
new @dot klammer; monospace email links.

sks/font/font.k

@@ -148,3 +148,8 @@ EB Garamond
 @@rightarrow.k : Right-pointing arrow: @rightarrow@ @@
 @@rightarrow.html :: &^#8594; @@
 @@rightarrow.tex :: $\rightarrow$ @@
+
+@@dot.k : Vertically entered dot @@
+@@dot.tex :: $\cdot$ @@
+@@dot.html :: ^00B7^ @@
+@@dot.txt :: ^00B7^ @@