[R6RS] global define and global variables (Chapter 1)

[dyb at cs.indiana.edu]

Since global variables are now a thing of the past, I don't think
that Chapter 1 should use the term global, either when describing
variable definitions (Section 1.4) or bindings for procedures
like + (Section 1.5).

Otherwise, I really like what Mike has written for Chapter 1.

Kent