Convtools

**Misc**

- [convtools-ita 22 ](https://github.com/itechart/convtools/issues/22)

**Bugfixes**

- Fixed name generation uniqueness issue
[convtools-ita 21 ](https://github.com/itechart/convtools/issues/21)

**Features**

- Introduced ``c.Mut.set_item`` and other mutations to be used in ``(...).tap(...) method
[convtools-ita 20 ](https://github.com/itechart/convtools/issues/20)

**Bugfixes**

- fixed ``gen_name`` usages (made ``item_to_hash`` mandatory)
[convtools-ita 19 ](https://github.com/itechart/convtools/issues/19)

**Features**

- * introduced ``c.optional`` collection items, which get omitted based on value or a condition
* improved converter generation so that inner conversions are not getting their own callable wrapper
* updated generated code variable name generation [convtools-ita 18 ](https://github.com/itechart/convtools/issues/18)

**Bugfixes**

- fixed aggregate issue: reduce(...).item(..., default=...) case [convtools-ita 15 ](https://github.com/itechart/convtools/issues/15)