Add support for FontForge time stamp table

Fixes https://github.com/behdad/fonttools/issues/56
diff --git a/Doc/documentation.html b/Doc/documentation.html
index 23dfefa..e2821fe 100644
--- a/Doc/documentation.html
+++ b/Doc/documentation.html
@@ -42,7 +42,7 @@
 The following tables are currently supported:
 <BLOCKQUOTE><TT>
 <!-- begin table list -->
-BASE, CBDT, CBLC, CFF, COLR, CPAL, DSIG, EBDT, EBLC, GDEF, GMAP, GPKG, GPOS, GSUB, JSTF, LTSH, META, OS/2, SING, SVG, TSI0, TSI1, TSI2, TSI3, TSI5, TSIB, TSID, TSIJ, TSIP, TSIS, TSIV, VORG, cmap, cvt, fpgm, gasp, glyf, hdmx, head, hhea, hmtx, kern, loca, maxp, name, post, prep, sbix, vhea and vmtx
+BASE, CBDT, CBLC, CFF, COLR, CPAL, DSIG, EBDT, EBLC, FFTM, GDEF, GMAP, GPKG, GPOS, GSUB, JSTF, LTSH, META, OS/2, SING, SVG, TSI0, TSI1, TSI2, TSI3, TSI5, TSIB, TSID, TSIJ, TSIP, TSIS, TSIV, VORG, cmap, cvt, fpgm, gasp, glyf, hdmx, head, hhea, hmtx, kern, loca, maxp, name, post, prep, sbix, vhea and vmtx
 <!-- end table list -->
 </TT></BLOCKQUOTE>
 Other tables are dumped as hexadecimal data.