Generic STM32 HAL based on the stm32duino core

This HAL is intended to act as the generic STM32 HAL for all STM32 chips (The whole F, H and L family).

Currently it supports:

• STM32F0xx
• STM32F1xx
• STM32F4xx
• STM32F7xx

Targeting the official Arduino STM32 Core.