Wire : New "begin" method for late call configuration

[jmchiappa]

Summary

This PR implements the following feature
begin(uint8_t sda, uint8_t scl);

Why ?
In some libraries, it requires a late call for SDA/SCL configuration. Have a look on u8g2 library. This method is supported by modern 32 bits architecture (ESP12, ESP8266).

How to test ?

1. Install u8g2 library

2. Open Graphic test

3. wire your OLED display to D6 (SCL) and D39 (SDA).

4. uncomment the line U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE, /* clock=*/ 6, /* data=*/ 39); // ESP32 Thing, HW I2C with pin remapping

5. compile and test

Known limitations
This needs to add defined(ARDUINO_ARCH_STM32) in u8g2 library in order to take benefits of this feature. The PR will be submitted very soon.

[fpistm]

Please fix astyle issue.
Else it seems reasonable and could avoid to use the setSDA/setSCL before Begin
Thanks

[fpistm]

@jmchiappa
Could you clean this PR to get only your change.
Thanks.

[jmchiappa]

@jmchiappa
Could you clean this PR to get only your change.
Thanks.

@fpistm,
Sorry I don't know how to do that...

[fpistm]

@jmchiappa
the main issue is that you made your PR on master. Then you pull the master.
So update you master to be inline with the original repo:

git remote add upstream https://github.com/stm32duino/Arduino_Core_STM32.git
git fetch upstream

then rebase your master on remote/upstream/master
git rebase -i upstream/master
Finally remove all unrelated commit and you can also squash the astyle fix.

You can see the Contributing.md for more details

[fpistm]

@jmchiappa
by squashing your PR, it is ok.
Anyway, a best practice is to create branch base on the master to avoid having all pulled commit in the PR 😉