Customproperties: Correct size for value field

Before this patch types "DateTime" and "Yes or No"
were one pixel too big in height.

Fix this by using the original aSize and aPos values, don't
depend on m_aYesNoButton size and position.

However there are some glitches with DateTime: If you scroll
some times up and down the list of "Type" the Date and Time
fields will get positioned somewhere left.
This has to be a problem of DateField and TimeField, because

m_aDateField.SetPosSizePixel( aPos, aSize );

and m_aTimeField get the same values as all other fields...

But this positioning error existed before this patch, too.

Change-Id: I793aebf39f5b6cb6e4b290f21a5dbcc7ce6ce964
Customproperties: Position DateTime correctly

No need to store the position of DateField and TimeField, because this
will not change if we choose another type. The only thing what changes
is the size of the DateField, because both "DateTime" and "Date" use
this field. And for this size we just rely on the size of m_aTimeField,
because it's the same as m_aDateField (for type DateTime).

Change-Id: Ic590c62d82d8f90576479e10be9d422326032d28
Customproperties: Correctly size Date

Old behavior:

1) Add a property of type "Date". DateField inside Value column uses
   the full width.
2) Increase the width of the dialog. Now the size of DateField in
   the Value column only uses the half width.

Solution:

Set a flag if the current type is of Date. So we can correct the size
after a dialog resize action.

Change-Id: I915a553b2f69aac1aea0ac5b24536db5709abfae