Force binary mode for file reading when embedding it.
It looks like sometimes on Windows images are not recognized as binary files.
Fixes #315
Fix #315: correct code to read binary file
Added Runtime.doc_string(). Fixes #350
Update copyright notice
Add Github-friendly CONTRIBUTING.md
Update CONTRIBUTING.md

Add signpost for people creating new issues.
Update CONTRIBUTING.md

Typo
Next version is 1.2.3
Reverting #324.  Fixes #386.  Closes #388
Clarification for realease process
Release 1.2.3
Master is targeted to 1.3.0 (again)
Proc.to_s return ASCII string, let's change pwd string to be ascii too. Fixes #150.
fixing links for the mailing list