faster gemm_int8, max speedup can be 2(int8 / float), add gemm_with_bias and add gemm_with_relu_bias.

fix a bug in feed kernel

Optimize im2col and implement winograd conv, bring 35% speed up for googlenet

add tanh kernel in FPGA v1 fixed #1314

fix #1310  update android development document

add split and transpose kernels for FPGA track close #1312

imp mobilenetssd

add kernels for V1 for FPGA track

imp concat kernel and update readme

add densebox test file 

 unify V1 & V2 style for FPGA track 

imp transpose and reshape kernel