Adds dub packaging.
Add package.json to be able to write "import dhsl;"
Rename package namespace from exent to dhsl (is it ok?)
Rename src to source.
main.d still is in the root directory to provide an example.
Rename package name to lowercase to match other packages.
DMD fixes, 32-bit fixes.
Merge pull request #1 from p0nce/master

Dub packaging, update to latest DMD, 32-bit fixes.