update librispeech conformer result

update librispeech conformer transformer config

fix the bug of doc in benchmark

Add the readthedoc

Revert the ctc loss to 2.1.2 and fix the bug of export model

fix the bug of import ctc decoder

[BUGFIX] Fix wget https with --no-check-certificate

compute cmvn before build vocab

update the wget script for openfst

[WIP] ctc loss api debug

multi workers for valid dataloader

argparse load conf from file

format code

rm useless swig dir

refactor raw ctc decoder into ctcdecoder, new join ctc/att decoder

using simple test for multi decode type, and using gpu

update the benchmark