* Rebaseline firmware to non-OS SDK version 3.0
* Note that SDK version 3.0 introduces the concept of a Flash Partition Table(PT). This is located at Flash offset 0x10000 in our firmware build.
* The firmware is now PT aware with both LFS and SPIFFS taking their partition size and location from the PT
* A new tool `tools/nodemcu-partition.py` is now used to initialise these data and can also download LFS and SPIFFS images to these partitions.
- Optimise ROTable accesses and interface
This includes some refinements to the ROTable cache which remove the linker cludges on the CROSS_COMPILE builds. Also keyhole tweaks to some of the Lua VM code to implrove runtimes.
I also noticed some compile time warnings during the build; the change to uz_unzip.c doesn't impact the compiled code, but does remove the compiler warnings.