Merge: Autocast and literal arrays

Small bugfixes

* forbid autocasts in combined assignments and literal arrays
* keep autocast information in transform
* rta visits implicit methods of literal arrays

Only the first one was the original bug I wanted to fix, the two others where discovered and solved while writing the PR.

Pull-Request: #1272
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>

diff --cc src/semantize/typing.nit
Simple merge