Implement "Custom" control, see details:

- A "Custom" control has WS_TABSTOP by default.
- The 'Class' option must be specified on control creation, e.g:
    Gui, Add, Custom, ClassScintilla ; creates a Scintilla control
- The g-label is triggered when the following messages are received:
    - WM_COMMAND. A_GuiEvent = Normal, A_EventInfo = HIWORD(wParam)
    - WM_NOTIFY.  A_GuiEvent = N,      A_EventInfo = lParam
- GuiControl/Get sets/retrievets the standard text (Set/GetWindowText)
Fix "Custom" control height calculation
Improved SoundGet/SoundSet support for Windows Vista and later.
Merge remote-tracking branch 'fincs/gui-custom-ctrl' into edge
Fix "Custom" control WM_NOTIFY handling
Fixed x64 warning caused by commit ee88fd78.
Fix another WM_NOTIFY bug, use ErrorLevel as the WM_NOTIFY return value
Merge pull request #21 from fincs/gui-custom-bugfix

Fix another WM_NOTIFY bug, use ErrorLevel as the WM_NOTIFY return value
Changed SoundSet/GetWaveVolume to work via SoundSet/Get on Vista+.
Merge branch 'edge'
v1.1.10.00