Update readSO.R

This is the updated version of the function that I had prepared to allow Mac users to get similar functionality ("clipboard" doesn't work for them). I had also modified it so that it automatically assigns an output data.frame with the generic and commonly used "mydf".
Merge in changes from @mrdwab. Closes #2.
stringsAsFactors = FALSE hard-code fixed

stringsAsFactors was incorrectly hard-coded in the "others" switch statement.
Merge pull request #3 from mrdwab/patch-3

stringsAsFactors = FALSE hard-code fixed
Add tmp.install.packages() function
Check if tempdir() is already in .libPaths()
Included tmp_install_packages function from @juba. Fixes #4.

Made some style corrections to the documentation for tmp_install_packages.
Added Julien to readme
added email address
Merge pull request #5 from mrdwab/patch-4

Added Julien to readme
Merge pull request #6 from mrdwab/patch-5

Added email for Ananda Mahto.
tmp_install_packages temp library is now inserted into the second place after the primary library and before the others.
Merge pull request #9 from sebastian-c/patch-8

tmp_install_packages temp library is now inserted properly, fixes #8.
Created internal function which accesses the clipboard on every OS.
Implements `readClip()` function
Merge remote-tracking branch 'mrdwab/patch-6'
Merged in readClip and readSO changes. Closes #13, closes #14.
Added new utility function: writeClip. Writes to clipboard on Windows and Mac.
Added Linux option using xclip.
Fixed readClip functionality on Mac.