Improve layer mask handling

[drashna]

Description

Add an explicit define for 32 bit layer mask, and set it as default.

Also, set default bitmask based on Dynamic Keymap layer count define to automatically handle this.

Types of Changes

• Core
• Enhancement/optimization

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[tzarc]

Everything seems to still build, despite Travis having a bit of a bad day.

[fauxpark]

Not Travis, Docker.

[tzarc]

It's Travis hitting up Docker too frequently... one of them is to blame, either way. Travis could use different IPs, do some caching, who knows.

[drashna]

It's Travis hitting up Docker too frequently... one of them is to blame, either way. Travis could use different IPs, do some caching, who knows.

We can also up the limit by including authentication, I believe. So .... there is that.