Added new PreDiveCheck info page:
In case a DiveO2 sensor is connected to the OSTC than the values of the DiveO2 internal pressure and temperature sensors may be used for predive checks. The pressure sensors is used for over / under pressure test and the values are visualized using a graph to make it easier to check if the pressure keeps stable. The temperature measurement gives an indication if the scrubber is getting active. This view is highly dependend on the surface temperature but may be useful e.g. for diving in european area.
In addition the values ofthe connected sensors are shown.
7 * an [STM32F427IIT6](http://www.st.com/content/st_com/en/products/microcontrollers/stm32-32-bit-arm-cortex-mcus/stm32-high-performance-mcus/stm32f4-series/stm32f427-437/stm32f427ii.html) as main processor. It is a Cortex-M4 processor with FPU, running at 180 MHz.
37 - **HAL_NVIC** _Nested Vector Interrupt Controller_: CORTEX IRQs used in `base.c` to handle buttons interrupts, in `gfx_engine.c` to manage VSYNC (screen's vertical sync) and in `stm32f4xx_hal_msp_hw2.c` to manage all other interrupts (ticks, DMA, DMA2D, TIM and USART).
40 - **HAL_SPI** _Serial Peripheral Interface_: implement the [standard SPI protocol](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus). Used to do full duplex communication between the two CPU in `data_exchange_main.c` to exchange dive settings and state, and in `externCPU2bootloader.c` to send firmware to _CPU2-RTE_.
42 - **HAL_UART** _Universal Asynchronous Receiver Transmitter_: serial communications used in `bonnexConnect.c`, `ostc.c`, `stm32f4xx_hal_msp_hw2.c`, `tCCR.c`, `tCpmm.c` and `tDebug.c`
47 - **HAL_DMA** _Direct Memory Accelerator_: automated memory transfers, used to manage SPI reception and transmission channels when communicating to main CPU.
50 - **HAL_I2C** _Inter-Integrated Circuit_ [bus controller](https://en.wikipedia.org/wiki/I2C) is another standard bus, used to connect the pressure sensor in `pressure.c`, the magnetic compass in `compass.c` and the battery state in `batteryGauge.c`. Initialisations are in `baseCPU2.c` and `stm32f4xx_hal_msp_v3.c`.
51 - **HAL_NVIC** _Nested Vector Interrupt Controller_: CORTEX IRQs used in `baseCPU2.c` to handle clock ticks, buttons and wireless state. In `spi.c` to know end of SPI transmissions. And in `stm32f4xx_hal_msp_v3.c` to setup various _I2C_ interupts.
55 - **HAL_SPI** _Serial Peripheral Interface_: implement the [standard protocol](https://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus). Used to do full duplex communication between the two CPUs. In `spi.c`, SPI1 is used to communicate to the maon CPU, and SPI3 to commicate to buttons.