Remove assert.

[zainab-ali]

This PR resolves #67 by removing the assert call entirely.

An attempt was made to make assert throw in #68 , however the assert function didn't compose well. Existing users of assert would need to rewrite their code to use expect, or use assert but with poorer syntax. For example:

pureTest("some test") {
  assert(1 == 1)
}

would need to be written as

pureTest("some test") {
  assert(1 == 1)
  success
}

Instead, we can remove assert entirely in favour of expect. As a follow up, we can have a scalafix rule to help users migrate.

[Baccata]

For the record : I've tried to play with different encodings to try and make assert work, by changing the definition of the various test methods to allow for it.

The issue is that weaver has been using overloads since forever to allow for various usecases semi-transparently. Overloads don't work well with polymorphism, leading the compiler to ask for more information from the user as it's unable to infer types as well as the current state.

So, although we could make it work by deleting the overloads before the next release, it'd lead to a level of inconvenience to existing users that I'm just not comfortable triggering.

Therefore, removal it is.