update function using new defun function

[k-okada]

see euslisp/jskeus#511 and euslisp/EusLisp#116 ,euslisp/EusLisp#300

• force generate defun.h header file
• use euslisp(9.24)'s new defun api roseus.cpp taht takes doc as argument, remove _defun
• add documentation string to defun functions
• add documentation string to defun functions, (roseus_c_util.c uses NULL because this is not exported functions)