Summary of changes:
* Some improvements in the UV features.
Auto UV Mapping, https://youtu.be/r3fW0XR2Wl4
UV Gridify and Straighten, https://youtu.be/uyO4KW_tgtA
UV Seam Edit, https://youtu.be/xtu4J0YF0Rk
* "UV Map" tool can be open in all selection modes.
* Some bug fixings.