Changes since Idris 2 v0.1.0

Compiler updates:

Data types with a single constructor, with a single unerased arguments, are translated to just that argument, to save repeated packing and unpacking. (c.f. newtype in Haskell)
- A data type can opt out of this behaviour by specifying noNewtype in its options list. noNewtype allows code generators to apply special handling to the generated constructor/deconstructor, for a newtype-like data type, that would otherwise be optimised away.
0-multiplicity constructor arguments are now properly erased, not just given a placeholder null value.

Language extensions:

%transform directive, for declaring transformation rules on runtime expressions. Transformation rules are automatically added for top level implementations of interfaces.
A %spec flag on functions which allows arguments to be marked for partial evaluation, following the rules from "Scrapping Your Inefficient Engine" (ICFP 2010, Brady & Hammond)

Library additions:

Additional file management operations in base
New modules in contrib for time (System.Clock); JSON (Language.JSON.*); random numbers (System.Random)

Other improvements:

Various performance improvements in the typechecker:
- Noting which metavariables are blocking unification constraints, so that they only get retried if those metavariables make progress.
- Evaluating fromInteger at compile time.
- In the run-time, reuse the old heap after garbage collection if it hasn't been resized, to avoid unnecessary system calls.
Extend Idris2's literate mode to support reading Markdown and OrgMode files. For more details see: https://idris2.readthedocs.io/en/latest/reference/literate.html
Fields of records can be accessed (and updated) using the dot syntax, such as r.field1.field2 or record { field1.field2 = 42 }. For details, see https://idris2.readthedocs.io/en/latest/reference/records.html

Changes since Idris 1