Add the "dbtotxt" utility program and the ability to read "dbtotxt" output

as a deserialized input database in the CLI, using the --hexdb option to
the ".open" command.

FossilOrigin-Name: e3bf1d3ea5f748c5142c2403813fdace5aedc1fc68f0dcd5eae40a2fe763fedb

Makefile.in

@@ -1292,6 +1292,9 @@ dbdump$(TEXE): $(TOP)/ext/misc/dbdump.c sqlite3.lo
 	$(LTLINK) -DDBDUMP_STANDALONE -o $@ \
            $(TOP)/ext/misc/dbdump.c sqlite3.lo $(TLIBS)
 
+dbtotxt$(TEXE): $(TOP)/tool/dbtotxt.c
+	$(LTLINK)-o $@ $(TOP)/tool/dbtotxt.c
+
 showdb$(TEXE):	$(TOP)/tool/showdb.c sqlite3.lo
 	$(LTLINK) -o $@ $(TOP)/tool/showdb.c sqlite3.lo $(TLIBS)