[ftinspect] Improve PostScript name display for MM/GX fonts.

Fixes #57 (closed) .

This MR consists of two parts.

The first one fixes the PostScript name display in the Font Info tab. Now the name shown in that tab is fixed to be the "basic" one specified for every named instances (e.g. NotoSansCJKtc-DemiLight). This commit also separates the FTC_FaceID used for retrieving information and for rendering (since rendering may change the face/size). Currently, the fix uses the highest bit in the FTC_FaceID to identify this. Let me know if there is better approach.

The second one adds a text box showing current constructed PostScript name with MM/GX coords included according to TN 5902. It also tracks the dirty state of each axis, so when no axis is touched by the user, the text box will show the basic PostScript name. When the user touches any axis, even when the value is set to the default value, the text box will show the constructed name. The user can use the "Def" or "Reset to Default" button to clear the dirty state on individual axis or all axes.

In spite of the discussion in the !37 (merged) comments, I decided to add the box into the MM/GX tab because the "constructed" PS name is highly related to the MM/GX context. Here's the current layout with a large and small window size:

What do you think about the layout?

Refer to commit messages for detailed description.