first commit
remove needless files
remove AUTHORS
remove LICENSE
update README
remove auto-generated files
extlibs should be placed under include/picrin/
import xhash, xrope, xfile, and xvect
fix xfile.c's include path
remove default library loader
remove time.c and system.c
remove eval.c and load.c
remove features and librarires procedures
remove file.c
change the interface of call/cc
remove call/cc (the alias to call-with-current-continuation)
remove macro definition helper procedures
downgrade xvect.h due to xvect's unknown bug
remove procedures originally introduced for compatibility
accept '(define (f a b) ...)' style in C level