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/document/document.cpp

@@ -26,6 +26,46 @@ std::string document(Machine& machine)
     }
 }
 
+// Print a console warning for each KT-WIDE-TABLE marker a table's runtime
+// width check (tex_width_check() in table.py) left in the xelatex log,
+// followed by a short :column_width primer.  Plain line scanning -- no
+// std::regex over the (arbitrarily large) log text.
+static void warn_wide_tables(const std::string& xelatex_log)
+{
+    bool any = false;
+    std::istringstream lines(xelatex_log);
+    std::string line;
+    while (std::getline(lines, line)) {
+        auto pos = line.find("KT-WIDE-TABLE ");
+        if (pos == std::string::npos) continue;
+        if (!any) {
+            std::cerr << yellow
+                      << "Warning: a table is wider than the text column "
+                      << "and extends past the right margin:\n";
+            any = true;
+        }
+        std::string detail = line.substr(pos + 14);
+        // The log's newline encoding can leave a trailing backslash.
+        while (!detail.empty() &&
+               (detail.back() == '\\' || detail.back() == ' '))
+            detail.pop_back();
+        std::cerr << "  " << detail << "\n";
+    }
+    if (any) {
+        std::cerr <<
+            "  The :column_width values and how they interact:\n"
+            "    fit    the column's widest entry, never wrapped\n"
+            "    fill   the width left over after the other columns, but\n"
+            "           no more than the widest entry; wraps when needed\n"
+            "    0.0-1.0  that fraction of the text column width\n"
+            "    *      the width left over, unconditionally (the table\n"
+            "           always spans the full text column)\n"
+            "  A long-text column set to \"fit\" never wraps and pushes\n"
+            "  the table off the page; give it \"fill\" instead.\n"
+                  << black;
+    }
+}
+
 extern "C"
 std::string tex_to_pdf(Machine& machine)
 {
@@ -67,6 +107,7 @@ std::string tex_to_pdf(Machine& machine)
                 throw Definition_error(ss.str(), Locator(), false);
             }
         }
+        warn_wide_tables(xelatex_log);
         /*
         if (std::stoi(machine.m_state.value("K_verbose_level")) < 2) {
             for (auto ext : word_split("tex out aux log toc")) {