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.

mac/klammer.cpp

@@ -214,6 +214,7 @@ void Klammer::copy_components(
     }
     for (auto c : cs) {
         m_body[c.target] = c.body;
+        m_body_generic[c.target] = (c.target == Target_set::general_name);
         m_varmap[c.target] = c.varmap;
     }
 }
@@ -287,6 +288,7 @@ void Klammer::copy_general_klammer_to_undefined(Target_set targets)
             if (m_body.count(target_name) == 0 && target_name != Target_set::declare_name) {
                 // std::cout << "  Copying to " << target_name << "\n";
                 m_body[target_name] = body;
+                m_body_generic[target_name] = true; // general body -> writer content
                 m_defloc[target_name] = loc;
                 m_varmap[target_name] = varmap;
             }