Added introduction to summer school and software engineering.
Delete 2013_07_08_Intro_Software_Eng.pdf

Was in wrong directory
Introduction to summer school and software engineering
Merge branch 'master' of https://github.com/dham/SummerSchool2013
Progress on Tuesday's lectures.
Merge remote-tracking branch 'upstream/master' into verification
Possibly nearly finished version of the verification slides.
Initial import of law notes.