Class "Cuda Runtime" fulfills function "tune" and adds corresponding testcase.
*Add: convCudnn::tune, convCudnn::cuDNNdescriptorAccess.
*Add: testcase tune.
*Fix: a brief bug in CPU Runtime.
* Fix: add warm-up and repetition in timing
* Add: CUDA runtime and float support
* Refactor: Cuda and Cpu runtimes inherit Runtime
* Add: environment script for Lotus
* Add: Lotus build instructions
* Update README.md
Co-authored-by: Liyan Zheng <liyan-zheng@outlook.com>