Makefile fixes

[cornet]

Few fixes to Makefile:

• Separate out install from build so un-privileged user can build
• Install header files to /usr/local/include/RF24 for easy inclusion when using this library: i.e. #include <RF24.h>
• Updated readme.md to reflect changes
• Cleaned up readme.md while I was in there
  • Use consistent syntax for headers
  • Tabs -> Spaces
  • Indent code by 4 spaces rather than using backticks
  • Fix table so it renders correctly in github

[TMRh20]

Thank you, could you add your readme.md updates to the copy in the RPi subfolder as well?

[cornet]

Yup can do, however would it make more sense to just have one of the readme files reference the other rather than having duplicate content ?

Another option could be to just symlink one to the other - I believe github honours this but could confuse anyone cloning the repo on Windows.

[TMRh20]

Well, yes and no? A reference equals a link, which equals another mouse click and page load on the users part. I like having it in the main RPi folder, since it displays prominently when viewing on GitHub, while users are provided with a local copy when they download the repo.

On the ohter hand, It may be better to refer them to the online version, since it will be kept up-to-date, so an html link in the repo readme and/or a symlink may be the way to go?

I'm not of a strong opinion one way or the other, as long as things are clear and consistent to users.