Added expect_raises macros and use them in specs. Also make assert_syntax_error create a spec with "it" (more concise)
Smarter parsing of macro bodies
Put restriction in to_s(io : IO) and reverted Int#to_s_in_base(radix) to Int#to_s(radix : Int)
Add IO restrictions in `to_s(io)` for std classes
Removed patch info from release version (we won't use that for now)
Automatic conversion of generic struct wrapper to C value
Small simplification in lexer macro, now that macros parse better
Allow implicit conversion to C types by defining a `to_unsafe` method. This removed the hardcoded rule for converting a `String` to `UInt8*` and also allows passing an `Array(T)` to an argument expecting `Pointer(T)`.
Don't go to metaclass when typing is_a? type. Fixes #162
Add Date class and initializer.
Implement Date#to_s.
Implement Date::Interval.

Includes addition, comparison, and to_i.

Also implement Int#days to create a Date::Interval.
Change Date to a struct, since it's a small immutable value object.
Implement Date#jdn to get the Julian Day Number.

Used the algorithm found in the Wikipedia article on [Julian Day].
Note that this is what Ruby calls Date#jd, but we feel that JDN is a
more precise term.

[Julian Day]: http://en.wikipedia.org/wiki/Julian_day#Converting_Julian_or_Gregorian_calendar_date_to_Julian_Day_Number
Implement Date comparisons.
Implement adding a Date::Interval to a Date.
Fix include Comparable to pass in type.
Change Date.for_jdn to overloaded variant of Date.new
Move date calculations to Date::Calendar class

Currently we only implement Date::Calendar::Gregorian, but have the
flexibility to add others later.
Add some documentation for Date class