Proto commits in daquexian/web-model-converter

These 4 commits are when the Protocol Buffers files have changed:

Commit:8a1fbef
Author:daquexian

support tf in tengine, use singleton tf proto

The documentation is generated from this commit.

Commit:13663bf
Author:daquexian
Committer:daquexian

Manage ncnn in submodules and find protoc by find_program

This commit does not contain any .proto files.

Commit:09abdce
Author:daquexian

Update for MNN

Commit:5ac3c9e
Author:daquexian

Add caffe2ncnn (doesn't fully work), improve existing code