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/image/image.k

@@ -18,8 +18,10 @@
 # @@image.html basename | width | height : @eval import image ; result = image.image(K) eval@ @@
 
 @@@argtype image_hpos |
-  horizontal position of an image
-  :pattern left^|center^|right^|none
+  horizontal position of an image: the element positions (center, left,
+  right, or a length used as the left margin), or none for an inline image
+  with no positioning container
+  :pattern 'element_hpos'^|none
   :default center
 @@@
 
@@ -29,7 +31,6 @@
   :width.length .5w
   @caption_arguments@
   :vmargin.bool true
-  :center.bool true
   :hpos.image_hpos
   :rel
   :abswidth.number 0.0