Fix use of translation functions

[DomClark]

Fixes some outdated or incorrect usage of translation functions.

• The pluginBrowser class has since been renamed to PluginBrowser, so translations using that context have been updated to use the new name.
• The context for audio backend name translations has been changed from setupWidget to AudioDeviceSetupWidget. This is consistent with the use of MidiSetupWidget for MIDI backends.
• VeSTige and VstEffect no longer pass strings consisting of a single integer id through tr.
• The line presName.replace(tr("\""), tr("'")); // QFileDialog unable to handle double quotes properly from vst_base has been changed not to use tr - it doesn't make sense to allow translators to override this and break QFileDialog.
• Static strings in InstrumentSoundShaping now use QT_TRANSLATE_NOOP rather than tr; tr has no effect there since the translations have not been loaded yet at that point.
• Some places in TrackContentObjectView, SetupDialog, and SampleTCOView had calls to tr factored out of ternary expressions, or into lambdas. This breaks lupdate, which can't recognise anything but string literals within tr calls. Calls to tr have been moved to wrap the literals.
• In cases where it is necessary to pass the contents of a QString to tr, toLatin1 has been changed to toUtf8, since this is the encoding Qt expects.
• PluginBrowser now translates descriptions in its tooltips for plugins that aren't subplugins.
• An unused static translation has been removed from InstrumentTrack.

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Linux

• Linux (AppImage): lmms-1.2.2.689-linux-x86_64.AppImage (build link)

Windows

• Windows 64-bit: lmms-1.2.2.689-mingw-win64.exe (build link)
• Windows 32-bit: lmms-1.2.2.689-mingw-win32.exe (build link)
• Windows 32-bit: lmms-1.2.2-msvc2017-win32.exe (build link)
• Windows 64-bit: lmms-1.2.2-msvc2017-win64.exe (build link)

macOS

• macOS : lmms-1.2.2.689-mac10.13.dmg (build link)

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[liushuyu]

Generally LGTM.

I will update the translation template after this PR gets merged. Thanks for your work!

[liushuyu]

Although this will certainly not break anything, I am not sure whether this will be effective since _pk.desc->description is dynamic.

[DomClark]

In the case that _pk.desc->subPluginFeatures is null, _pk.desc is a static descriptor from a plugin binary, e.g.:

lmms/plugins/Amplifier/Amplifier.cpp

Lines 34 to 45 in f34f894

	Plugin::Descriptor PLUGIN_EXPORT amplifier_plugin_descriptor =
	{
	STRINGIFY( PLUGIN_NAME ),
	"Amplifier",
	QT_TRANSLATE_NOOP( "PluginBrowser", "A native amplifier plugin" ),
	"Vesa Kivimäki <contact/dot/diizy/at/nbl/dot/fi>",
	0x0100,
	Plugin::Effect,
	new PluginPixmapLoader("logo"),
	NULL,
	NULL
	} ;

I'm not aware of any code that modifies these (we should probably make them const), and the description is clearly intended to be translated. This also matches the code in EffectSelectDialog:

lmms/src/gui/EffectSelectDialog.cpp

Line 237 in f34f894

labelText += "<p><b>" + tr("Description") + ":</b> " + qApp->translate( "PluginBrowser", descriptor.description ) + "</p>";

[DomClark]

Merge?

[liushuyu]

Merge?

I am very sorry for the late response. I think it's good to merge now.