Add parameterized 'timeout' to 'pulseIn' function

[rkast]

Problem

The 'pulseIn' function has a static 3 second timeout, I added another version to mimic Arduino. This has third parameter that specifies the number of microseconds to wait before timing out. Link to open issue is in 'Reference' section.

Solution

Adds addition parameter to a copied function and uses this value to calculate the number of systems ticks to wait, then uses this value in all of the timeout comparison statements

Steps to Test

This is my first contribution to Particle device-os, so I have yet to add testing

References

I'm new, so similar to the tests, I have yet to add an addition to the docs. But the opened issue can be found here:

https://github.com/particle-iot/device-os/issues/1379

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)