Remove limit of 16 sample files per project

[maks]

The current limit of 16 sample files per project is not necessary as while there is a limit of 16 sampler instruments per project, there is no need to limit the number of sample files to 16 as well.

One thing to be aware of here is that currently all samples in a project are loaded into flash on project load or when they are imported into the currently open project. Instead they should only be loaded into flash at the point where a sample is assigned to a sampler instrument.

Removing the limit should address the issues raised in #342 .