fixed _sys_read()/_sys_write() issues.
Merge pull request #204 from aozima/pulls

fixed _sys_read()/_sys_write() issues.
add SQLite 3.8.1 amalgamation source code
add SQLite-3.8.1 authority original source tree
add rtt complie macro SQLITE_OS_RTT
add rtt mutex support
add rtt memory management support
port complete SQLite-3.8.1 to RT-Thread
add vfs/fs porting
complete SQLite-3.8.1 porting, and auto generate porting code
add test/test10.c
fix declarative referential integrity
fix sqlite mutex/vfs/
fix the SQLite mutex free-fun cause a memory leak
orig config result tool
port rtt config orig env
build env component removal
modify the RTT is abbreviated error, change to be rtthread.
rename sqlite directory to SQLite-3.8.1/SQLiteLib
move SQLiteLib/SConscript file to SQLite-3.8.1/SConscript