writerfilter: refactor to be able to remove redundant Font class in doctok

Change-Id: I98516cbdb7e80a7dfe7048909ad4acb0418dbf9c
writerfilter: remove unused TC and PICF classes in doctok

Change-Id: Ibc84bc2ce0e31d52dfd0eb0e4a906145f0e559cb
writerfilter: remove unused Tplc class in doctok

Change-Id: Iec8680560bde8157e6e4c66417647f62b2feb8a8
writerfilter: two unused templates in doctok

Change-Id: Ia05ba411da4e7a6ea65945f23bc14fcdde5ab9cb
writerfilter: drop unused FDG, FTXBXS and FRD classes in doctok

Change-Id: I37c209b31bf47577b0f56b06fc49f15327f8c434