Add an option to asign bulk-loaded samples to existing "empty" positions.

[IcarusDream]

Sometimes, I create samples covering multiple full octaves to be used via an instrument.
Thus far I've been editing the sample maps manually from scratch every single time, a process that's both schematic yet tedious.
While there is option to assign specific sample numbers of an instrument before loading any samples (thus automatically creating new empty sample positions), when one loads the actual samples, they're by default assigned to new positions.
It's also worth noting that when importing via an existing "empty" sample position, the first sample in the loaded bulk will be covered by it, however the rest will be assigned to new positions.
This feels kind of impractical, because as said, there is an option to assign sample positions in the sample map of the instrument, but not an option to load samples to fill existing "empty" positions.
It would be good to have an option allowing one to choose whether the samples will be loaded to new positions or, will take existing ones.

[Saga Musix]

For the time being (and in general), you chould consider building SFZ instruments out of those samples, especially if you use them more frequently. SFZ is a simple textual description of where each sample belong on the keyboard, so you don't have to manually assign and tune the samples in OpenMPT. When importing instrument,s they will also delete all samples associated with the previous instrument loaded into the slot, so that also solves the second part of the problem.