added one fvmbook/chap20/rotate and a README_template.rst ...
Also fvmbook/convert_book.txt with first pass at some instructions.
added fvmbook/chap3/acousimple
changed dt_variable=True
updated instructions for converting book examples
added fvmbook/chap6/wavepacket
updated fvmbook/convert_book.txt
Added chap6/compareadv
Merge remote-tracking branch 'nthakkar/fvmbook' into fvmbook

* nthakkar/fvmbook:
  Added chap6/compareadv
Added chap10/tvb
Added chap12/efix
Merge remote-tracking branch 'nthakkar/fvmbook' into fvmbook

* nthakkar/fvmbook:
  Added chap12/efix
  Added chap10/tvb
Merge pull request #11 from rjleveque/fvmbook

Improved conversion scripts and added some fvmbook examples