edify extensions for OTA package installation, part 1

Adds the following edify functions:

  mount unmount format show_progress delete delete_recursive
  package_extract symlink set_perm set_perm_recursive

This set is enough to extract and install the system part of a (full)
OTA package.

Adds the updater binary that extracts an edify script from the OTA
package and then executes it.  Minor changes to the edify core (adds a
sleep() builtin for debugging, adds "." to the set of characters that
can appear in an unquoted string).
diff --git a/edify/lexer.l b/edify/lexer.l
index 4faef5d..cb5eb31 100644
--- a/edify/lexer.l
+++ b/edify/lexer.l
@@ -77,7 +77,7 @@
 else              { gColumn += yyleng; return ELSE; }
 endif             { gColumn += yyleng; return ENDIF; }
 
-[a-zA-Z0-9_:/]+ {
+[a-zA-Z0-9_:/.]+ {
   gColumn += yyleng;
   yylval.str = strdup(yytext);
   return STRING;