Bug with the maximum number of device types

[martaisty]

The bug:

The configured maximum number of device types _maxDevicesTypesNb doesn't represent the actual maximum of device types you can add. The exact number of devices is always one less than the configured value.

Root of the bug:

The condition that checks if it is possible to add more devices is incorrect.

The condition:

arduino-home-assistant/src/HAMqtt.cpp

Lines 188 to 190 in 0fc32a5

	if (_devicesTypesNb + 1 >= _maxDevicesTypesNb) {
	return;
	}

Initial values:

arduino-home-assistant/src/HAMqtt.cpp

Lines 21 to 23 in 0fc32a5

	_devicesTypesNb(0), \
	_maxDevicesTypesNb(maxDevicesTypesNb), \
	_devicesTypes(new HABaseDeviceType*[maxDevicesTypesNb]), \

Simple example to understand why it's incorrect

Let's say I want only 1 device type, so I pass maxDevicesTypesNb = 1 to the HAMqtt's constructor. Then I won't be able to add the device due to the incorrect if-check above. 0 + 1 >= 1 => true. The same is true for other numbers, having a maximum set to 7, you can add only 6 devices.