Marco Trevisan authored Aug 25, 2018 and Robert Roth committed Sep 05, 2018

Make possible to use integer literals to use numbers with base other than the
decimal without having to use the sub-fixed syntax.

So, now calculator recognizes numbers such as:
  - 0b10000001 and 0B01111110 (binary)
  - 0xdeadbeef and 0XBAADA555 (hex)
  - 0o01234567 and 0O76543210 and 01234543210 (octal)

And thus all the fancy operations like "0xff in dec" can be done now.

Added various tests to check the new behavior, and nothing broke for the old
cases.

Fixes #36