[MLBEDSW-297] Setup and run on Microsoft Windows

Various updates to make vela run and produce identical output on
Microsoft Windows.
* Fixed overflow errors
* Fixed compile warnings
* Avoid problematic numpy version
* Updated README.md

Signed-off-by: Fredrik Svedberg <Fredrik.Svedberg@arm.com>
Change-Id: Ie48c63a92a00c81b3247d07f05b75d881319ddbb
diff --git a/.gitignore b/.gitignore
index 2ea50a0..070ea6c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,5 +2,8 @@
 build/
 ethos_u_vela.egg-info/
 ethosu/*.so
+output/
+.vscode/
 .coverage
 __pycache__
+*.pyd