fix parallel line detection bug
fix parallel line detection bug

taylorhxu/tangram,xvilan/tangram,ceseale/tangram,TitoAgudelo/tangram,rosamcgee/tangram,ceseale/tangram,DHaylock/tangram,ceseale/tangram,taylorhxu/tangram,taylorhxu/tangram,zerebubuth/tangram,xvilan/tangram,TitoAgudelo/tangram,DHaylock/tangram,zerebubuth/tangram,rosamcgee/tangram,rosamcgee/tangram,zerebubuth/tangram,TitoAgudelo/tangram,xvilan/tangram,DHaylock/tangram,tangrams/tangram,tangrams/tangram