Check maximum window size dynamically

[jiixyj]

This should fix #85 .

[sdroege]

In my Rust port of this library I only check for overflows in the calculations of the audio_data here. This allows the user to select any value that can be addressed on the target platform, but also allows the user to select more than memory that is available.

Handling the case where not enough memory is available seems futile with modern OS that are overcommitting, and limiting the API to only allow up to a certain window size seems limiting for user code that might know that a bigger window size can be selected.

As such I would say that this change seems like the right thing to do: prevent overflows in the calculations (as they would cause bad things later on) but allow to allocate as much as the user wants as long as it can be represented.

[jiixyj]

Thanks for your thoughts on this! I merged this to master just now.