vm: use truncated division for Integers

[fyrchik]

When divisor is negative, the result is truncated towards
zero.

https://dotnetfiddle.net/qWwtyN

Closes #768 .

[codecov]

Codecov Report

Merging #773 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #773   +/-   ##
=======================================
  Coverage   64.31%   64.31%           
=======================================
  Files         141      141           
  Lines       12923    12923           
=======================================
  Hits         8311     8311           
  Misses       4209     4209           
  Partials      403      403

Impacted Files	Coverage Δ
pkg/vm/vm.go	78.01% <100%> (ø)	⬆️

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[roman-khimov]

Have you tested it for #768? Not that it's bad, but just to make sure.

[roman-khimov]

I guess it takes about 17-20 hours to reach this block now starting from zero. But to make a real test you have to start from zero, as there might be regressions.