added quotation mark
Added links for S and GPL.
Added new line to create section header
a property
Reworded how lists are printed to the console differently than vectors.
edits to section on factors
converted inspection of iris data frame to R code chunk
Made data-types image fit screen
remove spaces in code chunks
added tidy = FALSE to preserve nice indentation.
grammar edits
Accidentally blocked Rmd files in the ignore list

when i meant to hide the rendered md files.
Update and rename exercise.md.Rmd to exercise.md

Also added syntax highlighting to code blocks. Fixes #28
Merge pull request #25 from jdblischak/suggestions

Suggestions for R-basics