Updating the README.md.

Extended linux descriptions, changed build instructions for 1.6.x compilations.
	modified:   README.md
Changed README.md to replace mentions of 1.6.3 with those of 1.6.4
Added Wliu's Recommended changes, and cleaned up laziness-mistakes.
derp.
Changed some things around again.  I /think/ that's all.
I can't believe I missed that local repository line.  //Shame
typo
Added "/" note.
Trying to fix that annoying newline problem.
-.-
Maybe it will work in this editor..?
Bump required Forge version
Change Forge Version.
Merge pull request #455 from lluixhi/patch-1

Updates README.md to 1.6.x, and adds Mac OS X and Linux Specific instructions
Some work on changing how EmcValues work
More EMC work, it never ends!
More boring EMC stuff