cwebp: add some missing newlines in longhelp output

+ update README

Change-Id: Ia84d8857d575bc29ab3ce9c0f10264c042067e78
cwebp: fallback to native webp decode in WIC builds

this gives precedence to WIC, but attempts to decode the file as WebP if
it fails

Change-Id: I3d894f39a26aea88897a8ebd345139b82f74f312
Merge "cwebp: add some missing newlines in longhelp output"
Merge "cwebp: fallback to native webp decode in WIC builds"