Changes

Add __cast__ function and syntax

Add `__cast__(val, type)` function and syntax. Syntax is `(type) val`.
 (commit: 19d690c)

Warn on casts to same type + Error on impossible casts
 (commit: e2698cc)

Optimize __cast__()

- Mark `__cast__()` for constant and cached returns.
- Remove nested casts where the second executed cast is removed if the first executed cast passing ensures that the second executed cast will pass.
 (commit: c530cec)

Fix unknown Target for sugared __cast__() syntax
 (commit: 99f21b3)

Clone IVariables in IVariableList clone

Allows for not recreating a new `IVariable` for every assign operation.
 (commit: 541100b)

Optimize assign() to __unsafe_assign__ ()

Optimize `assign()` to `__unsafe_assign__ ()` when it is known that the `assign()` typecheck will always pass.
 (commit: 8a3b73d)

Reduce assign() runtime actions

- Do not redefine variables in variable list when not necessary.
- Unwrap IVariable values only once.
- Directly create new IVariable with correct values when necessary.
 (commit: e017fc2)

Fix compile error on post-assign non-cast parenthesis

Fixes compile error in the following example code:
```
@a = (1 + 2)
msg(123)
```
 (commit: bd0a1fe)

Add soft cast syntax compile test
 (commit: 4ddda9e)

Add cast to operators table in documentation
 (commit: 8ee2774)

Rewrite proc parameter execution

Fixes issue where variables in default parameter value expressions resolve to previous parameters instead of variables from the outer scope in runtime.
 (commit: 4f3dbd9)

Fix syntax mistake in SignatureBuilder.varParam() docs
 (commit: c4bc341)

Fix missing default value in untyped parameter declarations

Only affects static analysis.
 (commit: 9ecb896)

Fix core errors in throw(type, string) with invalid type

Fix core errors in `throw(type, string)` when passing non-exception types.
 (commit: c6af4a4)

Fix forward declaration procedure parsing

- Fix forward declaration procedures not parsing correctly if they are not followed by an AST term. This seems to only be an issue in interpreter mode as far as was tested.
- Add comments to clarify proc keyword rewriting logic.
 (commit: 507e0f0)

Fix checking functions too early during compile

Caused a compile error when a function did not exist but was inside a proper function_exists() or extension_exists() code block.
 (commit: 983b153)

Add salmon type to entity_spec
 (commit: 5004975)

Add arrow particle color to entity_spec
 (commit: 96e367e)