Assign proper interrupt handler function names to Core's i2c_hal.c

[geekbozu]

Problem

Using a core in I2C slave mode would cause a hard reset on pulling D0/I2C_SCL Low.

Cause

Improperly named function for I2C events and Errors.

Solution

Properly assign I2C interrupt service handler functions.

Steps to Test

Enable Wire library as slave. Pull D0 Low;

Example App

void reqEv(){
    return;
}
void setup() {
  Wire.begin(1);
  Wire.onRequest(reqEv);
}

void loop() {
 // nada needed
}

References

My thread on the problem.
https://community.particle.io/t/core-i2c-reboots-core/31551

---

Other thoughts.

This will probably fix quite a bit of I2C compatibility on the core as error handling of the peripheral will actually be functional now.
Bug was introduced in this commit cec9ade

Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[avtolstoy]

Thanks for the contribution! I've opened a PR #1309 that already fixes the incorrect naming of interrupt handlers. Unfortunately even with that fixed, Core still fails the tests. PR #1309 also includes a port of I2C slave implementation from Photon/P1.

[m-mcgowan]

Thanks for the contribution. Since this is superseded by #1309, I will close this. If you are able to help test #1309 to find out why it is still not passing the tests, that would be very much welcomed!