add some symbols about library
initial library support
add pic_lib
add global library table
add pic_equal_p
add pic_assoc
s/PICCONF/config/g
add pic_null_syntactic_env and pic_minimal_syntactic_env
add library operation methods
select the minimal library at first
change APIs of library functions
[workaround] load core syntaces initially
update submodules
implement import/export syntax
Revert "change APIs of library functions"

This reverts commit 0115ede4de05318535277549f5a40dd842ae9d30.

Conflicts:
	include/picrin.h
add pic_parse
let make_library return a library
set name to each library
select library during macroexpanding define-library
[bugfix] taking a wrong symbol for exporting