- fixed: Class File add a operator =
- reduce compile warning.
- remove K210 support.
- reorganize the library structure
- remove SFUD, It shouldn't be here
- remove more k210 relate code
- update .travis.yml
- update readme.
- make read return size_t
- fixed: Overloaded "=" operator needs to return * this
- support wio lite ai sdmmc.
- update examples