Merge pull request #1 from maleadt/master

Use STDERR instead of stderr_stream.
strcat->string
add->add!
New search returns ranges
expr->Expr (requires Julia 0.2)
Fix Expr constructors, ignore line nodes
Bump VERSION to 0.3.0-dev
Add rst documentation
Add pointer to docs in README
begins_with->beginswith
contains() is deprecated for strings, and search() semantics have changed.