BUGFIX: Print table without columns
BUGFIX: Format-List threw exception with empty objects
Reworked arithmetic operations

Arithmetic operations are now done in their native datatype and only
casted if an overflow happens. This leads to better precision in results.
Also, hex strings are now allowed to have a sign (+ or -) if (and only if) they are
used in arithmetic opertations.
Made tests explicit where PS breaks its own specification
REFACTOR: code for division is easier to understand
Try more datatypes for numeric conversion
Merge pull request #256 from sburnicki/print_empty_psobj

BUGFIX: Print table without columns
Merge pull request #257 from sburnicki/arithmetic_fix

FIX: Correct arithmetic operations
[BUGFIX] Fixed an assertion that was deprecated in NUnit.
[BUGFIX] Fixed one of the new integration tests.

Write-Host is completely unavailable here.
Merge pull request #259 from ygra/integration-test-fix

Fixed an error in one of the new integration tests.
Merge pull request #258 from ygra/ast-test-fix

Fixed an assertion that was deprecated in NUnit.