Remove remaining files from Covers.
Added scales
Adding MIME-type icon to the data directory for packagers to use
Fixes crashes on ctrl+drag.~
Merge pull request #275 from wongcc966422/issue273

Fixes crashes on ctrl+drag
Merge pull request #274 from diizy/stable-0.4

Adding MIME-type icon to the data directory for packagers to use
Refreshed all translation files
Fix a segmentation fault

Fix the segmentation fault caused by clicking on the "Cancel" button of the export dialog, as in issue #249.
Merge pull request #278 from M374LX/stable-0.4

Fix a segmentation fault
ComboBox: more checks for valid model + coding style

Before accessing the model, we have to check whether it is valid at all
in order to avoid a crash.

Closes #273.
Merge pull request #270 from zonkmachine/ghost-files

Remove remaining files from Covers. Fixes #264
Merge pull request #271 from zonkmachine/chromatic-scale

Added scales (chromatic scale again)
SongEditor: remove unused messing with engine's pointer to SongEditor

Back in time we obviously didn't manage to get construction dependencies
sorted so we needed to mess with the pointer to the SongEditor instance in
the engine class.

Thanks to Alexandre Almeida for pointing out this issue.

Closes #261.
VstEffect: added NULL pointer check in closePlugin()

We must not call methods on m_plugin in case there's no valid instance
e.g. due to missing DLL files.

Closes #245.
FxMixer, Mixer, AudioPort: minor coding style fixes
EffectChain: new argument hasInputNoise for processAudioBuffer()

Use the extra information to determine whether we need to process input
at all if plugin is not running anymore.

In FX mixer we now omit starting effects if no data has been mixed to
a certain FX channel. Instead let effects running until they finished.

First of multiple fixes for #267.
MixHelpers: added isSilent()

A simple function for testing whether a given sample buffer is silent.
Maybe we have to adjust/lower the threshold.
InstrumentTrack: skip processing for IPH-driven instruments when silent

InstrumentPlayHandle-driven instruments (i.e. instruments producing only
one sound stream for all notes) are running all the time even if no notes
are running. The plugin itself usually does not consume much CPU time
while silent but all effects afterwards inside LMMS unneccessarily
consume lots of CPU time for processing silent buffer.

Typical case: a song with lots of instruments like ZynAddSubFX.

With this change, all processing is skipped on silent buffers which
notably decreases CPU load for many projects. All effects in following
effect chains continue to run until they're silent as well.

Closes #267.
InstrumentTrack: always process silence at least one time

As of commit 1266278229a532f221ac9588fa5c85063d236ac8 silent buffers
from InstrumentPlayHandle-driven instruments are ignored. This is a good
thing but can beak PeakController instances attached to e.g. ZynAddSubFX.

Fixes playback of unfa-Spoken.mmpz.
FxMixer: no need to check for master channel

The m_used property will always be true for the master channel as soon
as data was received from at least one FX channel.