CHanged all user side/ CPU side code to double precision. Made filters to have neuronFunction etc code snippets formatted appropriately for float and double (trailing 'f' for float and 'f' on math functions, but neither for double).
Fixed a minor problem in the generate_run files where "make classolsim" for the Mbody examples led to compilation without optimization flags.
Now replaced with "make release".
Merge branch 'development' of https://github.com/genn-team/genn into development