Fixing typo in subset2

`r` was used when `sub` was intended.
Update Special-environments.rmd

I think x (in the case of curve2) and .it (in the case of with_conn) should be assigned in the newly constructed environment, not in the parent.frame(). This way they are properly enclosed.

Also looks like you had a typo in eval'ing the with_conn code in the context of env when it should have been env2.

Great book!
Merge pull request #60 from zackham/patch-1

Update Special-environments.rmd
Fixed typo
Fixed typo
Merge pull request #62 from kdauria/patch-3

Fixed typo
Merge pull request #61 from kdauria/patch-2

Fixed typo
Merge pull request #59 from seancarmody/patch-1

Fixing typo in subset2
Update C-interface.rmd

correcting repetition of "code"
Update Function-operators.rmd

"functions that take one (or more) function" - "functions that take one (or more) functions"
Update Data-structures.rmd

avoid repetition of "into".
Update Functions.rmd

change "It's" to "R's" - it's not immediately clear what "It" is in the context of that paragraph.
Merge pull request #64 from Ironholds/patch-1

Update C-interface.rmd
Merge pull request #65 from Ironholds/patch-2

Update Function-operators.rmd
Merge pull request #66 from Ironholds/patch-3

Update Data-structures.rmd
Merge pull request #67 from Ironholds/patch-4

Update Functions.rmd
Update Data-structures.rmd

"most more complicated" - "most of the more complicated". It changes the meaning somewhat, but it's still true.
Merge pull request #68 from Ironholds/patch-5

Update Data-structures.rmd
Update Exceptions-Debugging.rmd

Some miscellaneous copy tweaks
Merge pull request #69 from Ironholds/patch-8

Update Exceptions-Debugging.rmd