Added capability of overriding AmpMinimumLevel in the .cmb file https://github.com/GrandOrgue/grandorgue/issues/782

[oleg68]

This is the first PR related to #782

This PR

• Introduces GOEnclosure::m_DefaultAmpMinimumLevel loaded from the ODF
• Adds Load and Save m_AmpMinimumLevel from/to .cmb
• Adds the GetAmpMinimumLevel and SetAmpMinimumLevel methods for future use
• Changes the data type of m_AmpMinimumLevel and m_MIDIValue to uint8_t
• Renames GoEnclosure::Set to SetMidiValue, GoEnclosure::GetValue to GetMidiValue
• Extracted the common part of GOEnclosure::Init and GOEnclosure::Load tp GOEnclosure::LoadFromCmb
• Added an advanced version of GOEnclosure::SetIntMidiValue

This PR does not add any GUI for redefining AmpMinimumLevel. It will be added in a future PR after some discussion in #782

[larspalo]

@oleg68 I think you should focus on adding this setting only for the enclosures supplied by GO itself (on the Panels).

[oleg68]

@oleg68 I think you should focus on adding this setting only for the enclosures supplied by GO itself (on the Panels).

This PR does not add any setting, but only adds the capability of storing the user defined value in .cmb. Do you have any reasons opposite this PR?

[oleg68]

@larspalo @rousseldenis could you approve this PR?