Error redesign

[paul-schaaf]

closes #798

Changes:

• adds Error enum (AnchorError or ProgramErrorWithOrigin)
• adds type Result<T> = Result<T, Error> thats to be used instead of ProgramResult
• adds error! macro that creates AnchorError with source info and wraps it inside an Error
• adds err! macro that expands into Err(error!(#error_code))
• adds source! macro that can be used to enrich ProgramErrors with Source information
• renames #[error] to #[error_code]
• adjust ts library so it can parse custom errors from real tx instead of just simulated ones

[armaniferrante]

No need to change. But FYI this can be rewritten as

AnchorError {
  error_code_number,
  ..
  }

[armaniferrante]

Looks good to go after the tests pass once more.

[archseer]

• adds err! macro that expands into Err(error!(#error_code))

And what does error! expand to? Why can't this be Err(MyError::A.into())?

[paul-schaaf]

the full expansion can be seen in lang/attribute/error

.into() doesnt work because we want to return an error with file and line info and that info should be the same line as the error! call

[paul-schaaf]

Err(MyError::A.into()) this also works now but it wont include source information