Version 1.8 (2019-3-10)

This is a short release (2 months instead of the usual 3). Since this is an even

release, the plan was to write a testing system while leaving the core alone.

However, the testing system needs several internal adjustments that don't fit

with an even release. As a result, this release is being pushed early. The next

release, 1.9, will absorb the extra month. This should not happen again.

* Symtab symbol internals have been shuffled around a bit. These adjustments

have no bearing on the workings of scripts. They were done to make a future

inspection package easier by having elements such as the next pointer of a

symbol in a consistent place.

* lily.h now properly marks `lily_import_use_package_dir` as being available. It

was available, but due to a typo, `lily_import_use_local_dir` was mentioned

* Store the main module's path as a string literal. This lets spawni not worry

about the lifetime of the path that it's sending. (#426).

* `__function__` in `__main__` no longer crashes (#420).

* Fix error message display when shadowing a class constructor parameter (#421).

* Fix module lookup not using the proper path, causing modules to be created

that did not need to be. Consider a situation where 'a' directly imports 'b'

and 'c'. Module 'b' directly imports 'c'. All modules are in the same

directory, so there should only be one copy of 'c'. Because the wrong path was

used, 'a' and 'b' had different copies of 'c'. (#423, reported by @Zhorander).

* Super ctors can't use base members in init (#424).

Version 1.7 (2019-1-10)