Follow-Up of 7db3fa94a1 .
This was done by setting `CMAKE_C_INCLUDE_WHAT_YOU_USE` and
`CMAKE_CXX_INCLUDE_WHAT_YOU_USE` to (broken down into multiple lines here,
note, all below `FL/x.h` is not required for C):
```
include-what-you-use;
-Xiwyu;--mapping_file=/usr/share/include-what-you-use/qt5_11.imp;
-Xiwyu;--keep=*/xmmintrin.h;
-Xiwyu;--keep=*/lmmsconfig.h;
-Xiwyu;--keep=*/weak_libjack.h;
-Xiwyu;--keep=*/sys/*;
-Xiwyu;--keep=*/debug.h;
-Xiwyu;--keep=*/SDL/*;
-Xiwyu;--keep=*/alsa/*;
-Xiwyu;--keep=*/FL/x.h;
-Xiwyu;--keep=*/MidiApple.h;
-Xiwyu;--keep=*/MidiWinMM.h;
-Xiwyu;--keep=*/AudioSoundIo.h;
-Xiwyu;--keep=*/OpulenZ/adplug/*;
-Xiwyu;--keep=QPainterPath;
-Xiwyu;--keep=QtTest
```
FAQ:
* Q: Does this speed-up a completely fresh compile?
* A: No, I measured it.
* Q: Does it speed up anything else?
* A: Yes. If you change one header, it can reduce the number of CPP files
that your compiler needs to recompile, or your IDE has to re-scan.
* Q: What other reasons are for this PR?
* A: It's idiomatic to only include headers if you need them. Also, it will
reduce output for those who want to use IWYU for new PRs.
Background:
This is just a remainder PR of what I planned. My original idea was to setup
a CI which warns you of useless includes (but not of all issues that IWYU
complains about). However, I could not see that this was favored on Discord.
A full IWYU CI also has the problem that it (possibly??) needs to compile
with `make -j 1`, which would make CI really slow.
However, for that plan, I had to fix the whole code base to be IWYU
compliant - which it now is.

LMMS
Cross-platform music production software
Website ⦁︎ Releases ⦁︎ Developer wiki ⦁︎ User manual ⦁︎ Showcase ⦁︎ Sharing platform
What is LMMS?
LMMS is an open-source cross-platform digital audio workstation designed for music production. It includes an advanced Piano Roll, Beat Sequencer, Song Editor, and Mixer for composing, arranging, and mixing music. It comes with 15+ synthesizer plugins by default, along with VST(i) and SoundFont2 support.
Features
- Song-Editor for arranging melodies, samples, patterns, and automation
- Pattern-Editor for creating beats and patterns
- An easy-to-use Piano-Roll for editing patterns and melodies
- A Mixer with unlimited mixer channels and arbitrary number of effects
- Many powerful instrument and effect-plugins out of the box
- Full user-defined track-based automation and computer-controlled automation sources
- Compatible with many standards such as SoundFont2, VST(i), LADSPA, GUS Patches, and full MIDI support
- MIDI file importing and exporting
Building
See Compiling LMMS
Join LMMS-development
If you are interested in LMMS, its programming, artwork, testing, writing demo songs, (and improving this README...) or something like that, you're welcome to participate in the development of LMMS!
Information about what you can do and how can be found in the wiki.
Before coding a new big feature, please always file an issue for your idea and suggestions about your feature and about the intended implementation on GitHub, or ask in one of the tech channels on Discord and wait for replies! Maybe there are different ideas, improvements, or hints, or maybe your feature is not welcome/needed at the moment.