Replace wget with curl

- OSX doesn't ship with wget.
- Neither curl nor wget ship with mingw
- WF libraries depend on libcurl
- curl is lighter and more flexible than wget
- Change wget -c (continue) to curl -C -
- Change wget -P $PATH to curl -o $PATH/$FILE
- Change wget to curl -L (follow redirects)
- Change wget without -p to curl -OL (save to file similar to name
  of downloaded file)