Add log base 2 button

[An-anonymous-coder]

Is your feature request related to a problem? Please describe.
I use log2 frequently, and it's frustrating to do log(x)/log(2) to achieve the same result.

Describe the solution you'd like
There should be a button for a base-2 logarithm.

Describe alternatives you've considered
Customize the calculator buttons yourself.

Additional context
Other calculators have extended functionality when the device is in landscape mode. This one is missing many special buttons such as custom roots, custom logarithms, etc.

[Darkempire78]

Add a customize system will be painful