Fix a missed Common Lisp to R substitution
Merge pull request #614 from rzarev/patch-1

Fix a missed Common Lisp to R substitution
Update Expressions.rmd
Merge pull request #615 from michaelmikebuckley/patch-1

Update Expressions.rmd
Update OO-essentials.rmd
Merge pull request #616 from perryjer1/master

Update OO-essentials.rmd
fix typos
Merge pull request #617 from perryjer1/master

fix typos
fixed typos
Merge pull request #618 from perryjer1/master

fixed typos
Fixing a typo
Merge pull request #619 from polmath/patch-1

Fixing a typo
Update C-interface.rmd
Merge pull request #620 from michaelmikebuckley/patch-2

Update C-interface.rmd
Update Introduction.rmd
Merge pull request #621 from michaelmikebuckley/patch-3

Update Introduction.rmd. Added section labels - "{#colophon}" etc.
TYPO: asLogical() takes LGLSXP (was INTSXP)
Merge pull request #622 from HenrikBengtsson/patch-1

TYPO: asLogical() takes LGLSXP (was INTSXP)
Update Introduction.rmd
Merge pull request #623 from michaelmikebuckley/patch-4

Update Introduction.rmd. My typo!