Merge pull request #50 from jemc/master

Problem: it's annoying to write CI systems by hand
Problem: Readme is written in pure markdown
Solution: Use gitdown to generate markdown readme.
Problem: Typos, wrong information and huge toc
Solution: fix typos, add correct information and shrink toc
Problem: Wrong grammar
Solution: fix grammar
Merge pull request #51 from sappo/master

Problem: Readme is inconsitent with explanations in project.xml
Problem: it's painful to make new .gitignore by hand

Solution: generate this first time

Fixes #45
Problem: need way to specify model script

Solution: add 'script' property; if this is set then generate
appropriate gsl line. Note: we set -topdir:.. so the script works
from within src. (E.g. Java generates into ../main not into src).

Fixes #42
Merge pull request #52 from hintjens/master

Problem: it's painful to make new .gitignore by hand
get additional params from nested param elements.
Merge pull request #53 from mknoszlig/master

Problem: can't freely specify additional model parameters in project.xml