Add type-checking and structural checker dialects
Add super and outer to type checking dialects
Resolve incorrect outer in inherited object
Make empty lists raise error for first/last
Add typechecking dialects to sample lists
Tweak gracelib.js to help typechecker
Complete type combinators and self/outer typing
Fix some methods returning undefined in JS
Avoid JS checkmethodcall errors when too few args
Add `make samples` target
Fix syntax error in JS def check
Add declarative type and method declarations
Add asString to JS exceptions
Add structural example to sample index
Return done instead of undefined across JS
Ensure if()then() returns a value
Save start line of request in AST node
Add quick "fail" to checking dialect
Add declarative fail-when to checking dialect
Add "check" method to checking dialect

This method gives interface compatibility with the previous dialect for
writing dialects.