Simple C-version Smart-Pointer is implemented.
LRU cache is newly implemented and 'hash' is improved to support LRU cache.
'ylist' code becomes simple and clear.
Improvement(mempool) & code-beautify.

Exception(OOM)-handling is improved for mempool.
Missing license comments are added.
Some misc. code beautifies.
'common.h' is renamed to 'ycommon.h' and included at public header.
Make file is changed to apply all changes. + .gitignore is updated.