Use arrays to reduce repetition in gstccdec. Also merged the add_srcpad functions into gst_cc_decoder_get_srcpad,
and made the function work if a pad already exists.
Simplify `gst_cc_decoder_user_data_decode` more by merging the 708 sections and removing unnecessarily complicated `for` loops.
Move more macros into gstccdec.c.
Use <= when checking DTVCC_LENGTH - 2.
Merge pull request #7 from cablelabs/ruih/use-arrays-to-reduce-repetition

Ruih/use arrays to reduce repetition