splash: framebuffer test program

Change-Id: I7e045a4c6cec476615057f46f530693c0a2a17e0
splash: use parameters provided by the fb driver

Certain parameters, such as screen resolution, differ between
monitors. Enhance the splash program to dynamically configure
itself.

Change-Id: I49b0a3704decb7cb4633a1ee424b0419a1d67cf0
tsl2550: driver for the TSL2550 light sensor

Change-Id: I9e1c87132404509ffec8bf22a8c6cc993df1aa73
sht21: driver for the SHT21 humidity & temp sensor

Change-Id: Ia71168e394a7b260019e74973db6c9d75d3d4482