Bugfix for inverted protocols that leave transmit pin HIGH after sending

Add support for HS2303-PT

Make the library compatible with the ESP32 architecture

Remove unnecessary conditions from examples

See issue #119

Changed the order of "mySwitch.setProtocol(2);" and "mySwitch.setPulseLength(320);", so setting the PulseLength will work when both lines are commented out. See issue #117

PT2260/SC2260 support + small fix

i.e.:
Decimal: 4685616 (24Bit) Binary: 010001110111111100110000 Tri-State: F0F1F1110100 PulseLength: 146 microseconds Protocol: 1
Raw data: 4548,224,372,520,60,216,404,184,400,192,396,492,92,484,120,468,132,148,460,444,136,456,132,460,140,448,144,444,152,440,152,440,160,120,484,112,472,428,152,440,156,124,480,116,472,124,468,132,452,
Decimal: 4685571 (24Bit) Binary: 010001110111111100000011 Tri-State: F0F1F1110001 PulseLength: 149 microseconds Protocol: 1
Raw data: 4612,164,432,476,120,148,460,132,460,136,460,456,136,448,156,436,172,92,508,420,172,420,180,416,184,412,180,412,192,404,192,408,196,68,536,60,528,76,516,84,508,92,500,100,488,432,164,424,176,

1. get rid of unrecognized category warning in Arduino IDE. It doesn't seem to support multiple categories
2. add esp8266 to the list of architctures to avoid warnings about incompatible architecture. This library works on esp8266

Updated README.md to include HT6P20X

Added transmit and receive support for devices using Holtek HT6P20X s…

@PlatformIO Library Registry manifest file

Added Arduino IDE build and more boards (attiny24/25, esp01, uno) to …

Fix Travis CI build

This reverts commit 067ab194.

Added transmit and receive support for devices using Holtek HT6P20X series encoders via a new protocol. See the datasheet for the waveform. This protocol uses pulses that start low instead of high requiring a few more changes than simply adding to the proto struct.

The old (and new again) semantics are that the bits in 'data' are sent
starting from the MSB. This had regressed recently to sending bits
starting at the LSB, as part of my refactoring.

Should resolve #52