New feature for 1.2.4

Version 1.2.4 is in reviewing stage. Here are features of 1.2.4
- Support New Image Format: dng, cr2, crw, fpx, fpix, raf, dcr, mrw, nef, orf, exr, qti, qtif, hdr, sgi, srf, targa, tga
- Database optimization to improve thumbnail display speed
- Show Map snapshot if there is GPS info in Exif
- Delete Current Image by hotkey
- Improve the zoom-in image quality by Lanczos filter