Check inferred type against ascription in variable declaration

[megatron00999]

Fixes #915

Code such as below now throws UnexpectedType exception.

val price: Long  = ((reserveIn.toBigInt * precisionFactor) / hodlCoinsCircIn)

[megatron00999]

The change looks far bigger than what it actually is because of the indentation change which I had to do as part of doing the type validation at the end.

I've highlighted the main logical changes as comments. Rest is just indentation.

[megatron00999]

@aslesarenko @kushti Please review.

[aslesarenko]

@megatron00999 please rollback indentation so that I can review and analyze the changes. Then once approved, you can add identation back as separate commit.

[megatron00999]

@aslesarenko Done, please take a look.

[aslesarenko]

@megatron00999, please look at the failing tests.
It seems the check cannot be done as part of typing transformation.
It should be done as separate whole tree traverse.