revise the Two White Parts comments in gc.c
Merge pull request #1397 from Fleurer/revise-comments-on-white-colors

revise the Two White Parts comments in gc.c
Move home variable into readline ifdef
If readline is enabled add readline to libraries to link
display multiple authors better.

Before:
Copyright (c) 2013 ["a", "b"]

After:
Copyright (c) 2013 a, b
"spec.author" is better for single-author gems.

"spec.author=" expects a String represents a single author.
"spec.authors=" expects an Array which is a list of multiple authors.

http://guides.rubygems.org/specification-reference/
Check home is null
gc: add comments for Generational Mode
String `=~` and `match` to work with pluggable Regexp; close #1398
Merge branch 'master' of github.com:mruby/mruby
Merge pull request #1400 from carsonmcdonald/readlinewarnfix

Move home variable into readline ifdef
Merge pull request #1399 from carsonmcdonald/readlinelinkfix

If readline is enabled add readline to libraries to link
resolve conflict
Merge pull request #1402 from mattn/check_home_is_null

Check home is null
Merge pull request #1403 from Fleurer/comments-generational-gc

add comments for Generational Mode in gc.c