Yaramod

* Re-release of v2.12.0 because it was broken on git

* Enhancement: Bump the required C++ standard from 14 to 17.
* Enhancement: Replace uses of `nonstd::optional` from `dep/optional_lite` with standard C++17 `std::optional`. Remove the `optional_lite` dependency.
* Enhancement: Replace uses of `mpark::variant` from `dep/variant` with standard C++17 `std::variant`. Remove the `variant` dependency.

* New: Added `cuckoo.process.modified_clipboard()`, `cuckoo.network.connection_ip()`, `cuckoo.network.connection_country()` and `cuckoo.network.irc_command()`.
* New: Module `phish`.

* New: Added `cuckoo.process.api_call()`

* New: Interface for obtaining internal representation of regular expressions ([29](https://github.com/avast/yaramod/issues/29)).
* New: Interface for visitor over regular expressions ([33](https://github.com/avast/yaramod/pull/33)).

* New: Added support for `pe.iconhash()` function.