implement nil#to_a, #to_f, #to_i.
fix out-of-bound access on compiling empty blocks.
add IIJ.
implement IO and File class

 * define IOError
 * implement IO and File class for GC.
 * modify Makefile to include IO and File
extend Kernel module.

 * added method list
   * #sleep
   * #system
   * #exit
Regex class: fix build error and, modify default enable.

* fix build error.
* implement method
  - ::new
  - #match
* add enc/ascii.c file from oniguruma-5.9.2
implement ENV object.
add posix test case to IO and File class.
add UNIXSocket (WIP).
Merge branch 'socket' into iij
About our repository
implement Array #- #& #| #uniq #uniq!
update README.md
remove unneeded test code.
license.
TCPSocket
add TCPSocket.
implement String strip methods by mrblib. and add test code.
Digest::MD5/RIPEMD160/SHA1/SHA256/SHA384/SHA512.
Merge branch 'digest' into iij