This patch implements a couple of enhancements to the synthesizer
engine:
* Each track has a volume control.
* The input and tooltips for all controls are improved.
* The noise channel is pitched, which allows for basic drum synthesis.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
Because it's what it really is. A frame is composed of 1 or more samples, in
the case of SerenityOS 2 (stereo). This will make it less confusing for
future mantainability.
When you reset() a Track, you need to set the piano roll iterators back
to the first notes.
Fixes#2578. The bug was due to pressing export between 2 notes - the
tracks were never told to go back to the first note.
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
