fix three documentation typos

"know" -> "known" and
"must not have an ERRORs" -> "must not have *any* ERRORs"
"it's" -> "its"
The R CMD option rebuild vingettes has been renamed build vingettes
Merge pull request #521 from statwonk/master

The R CMD option rebuild vingettes has been renamed build vingettes
Re-document
Re-generate svn docs
Remove unused svn-path.Rd file
document: use namespace env instead of package env
Fix a typo ("all all").
Merge pull request #528 from craigcitro/patch-1

Fix a typo ("all all").
Merge pull request #517 from scottkosty/patch-2

fix three documentation typos
Update cran notes
Re-roxygenise
Re-re-roxygenise
Improve release docs
Merge remote-tracking branch 'hadley/master'
describe the behavior of updated `source_url` for multiple files.

remove get_fileext, use tools::file_ext instead
Merge remote-tracking branch 'origin/master'