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/table/table_cell.py

@@ -12,7 +12,8 @@ class Cell:
     def __init__(self, text, font, hpos,
                  top, right, bottom, left,
                  left_all, right_all,
-                 rowspan, colspan, first_column=False, hpos_forced=False):
+                 rowspan, colspan, first_column=False, hpos_forced=False,
+                 fit_class="", flush_left=False, flush_right=False):
         self.text = text
         self.font = font
         self.hpos = hpos
@@ -23,6 +24,17 @@ class Cell:
         self.rowspan = rowspan
         self.colspan = colspan
         self.first_column = first_column
+        # html only: the class(es) clamping a 'fit' column's cell to its
+        # widest entry -- "Wfit Wpct" in a full-width table, "Wfit" in a
+        # content-sized ('fill') table, "" when not a fit column.
+        self.fit_class = fit_class
+        # Cell sits on a table edge with no outer vertical line: its outer
+        # padding (html) / \tabcolsep (tex, via @{}) is removed so the text
+        # aligns with the text margin.  A tex \multicolumn replaces the
+        # whole preamble entry including the @{}, so edge cells must
+        # re-emit it in their own spec.
+        self.flush_left = flush_left
+        self.flush_right = flush_right
         #print("Cell:", text, hpos)
 
     def __str__(self):
@@ -47,6 +59,12 @@ class Cell:
             if pred:
                 result.cls(cls_name)
         result.cls(f"H{self.hpos}")
+        if self.fit_class:
+            result.cls(self.fit_class)
+        if self.flush_left:
+            result.cls("Fl")
+        if self.flush_right:
+            result.cls("Fr")
         return result.str()
 
     def tex(self, debug=False): # , left_line, right_line):
@@ -70,6 +88,10 @@ class Cell:
                 pos = "|" + pos
             if self.border.right:
                 pos = pos + "|"
+            if self.flush_left:
+                pos = "@{}" + pos
+            if self.flush_right:
+                pos = pos + "@{}"
             return f"\\multicolumn{{{self.colspan}}}{{{pos}}}{{{result}}}"
         remove_left = self.border.left_all and not self.border.left
         remove_right = self.border.right_all and not self.border.right
@@ -83,6 +105,10 @@ class Cell:
                 pos = "|" + pos
             if self.border.right_all and self.border.right:
                 pos = pos + "|"
+            if self.flush_left:
+                pos = "@{}" + pos
+            if self.flush_right:
+                pos = pos + "@{}"
             result = f"\\multicolumn{{1}}{{{pos}}}{{{result}}}"
         return result