update the structure of the code of im2col.cpp

update README

update README

separate C = A * B + bias and C = A * B + C in Gemm

repair bug of bias is nullptr

fix im2col in case of 2*2 input

repair bug of  predict ten times' diffent result in genet

fix #826

add HasAttr() for op_param.h and check "inplace" attr in reshapeOp fixed #818

fix annotation of unit test of net

imp fusion_conv_add_prelu and fusion_conv_add_add_prelu op

# Conflicts:
#	src/framework/program/program-optimize/node.cpp
#	src/operators/fusion_conv_add_add_prelu.cpp
#	src/operators/fusion_conv_add_add_prelu_op.h
#	src/operators/fusion_conv_add_prelu_op.cpp
#	src/operators/fusion_conv_add_prelu_op.h
#	src/operators/kernel/arm/conv_add_add_prelu_kernel.cpp
#	src/operators/kernel/arm/conv_add_prelu_kernel.cpp
#	src/operators/kernel/central-arm-func/conv_add_add_prelu_arm_func.h
#	src/operators/kernel/central-arm-func/conv_add_prelu_arm_func.h
#	src/operators/kernel/conv_add_add_prelu_kernel.h
#	src/operators/kernel/conv_add_prelu_kernel.h
#	src/operators/math/gemm.cpp
#	src/operators/math/gemm.h
#	src/operators/math/math_function.cpp
#	src/operators/op_param.h
#	tools/op.cmake

update unit test and jni