Added support for LibreTiny IoT chips

[Phil1pp]

github.com/libretiny-eu/libretiny

Tested with CBU chip over WIFI

[env:BK7231N_ip]
platform = libretiny
board = cbu
framework = arduino
build_flags =
  -DMASK_VERSION=0x57B0
  -DSMALL_GROUPOBJECT
  -DKNX_NO_SPI
  -DKNX_FLASH_OFFSET=0x1DB000

[Phil1pp]

I don't understand why linking fails even though randomSeed is defined here:
wiring_math.cpp

[thewhobox]

Mabye millis() is unsigned long but the function needs uint32_t.
Because there ist no function with parameter seed as unsigned long it cant link it.

If i make these changes in line 61 it works:

uint32_t seed = millis();
randomSeed(seed);

[Phil1pp]

Are you sure that this change should work?
I wasn't able to compile it locally and also online it failed.

I only got it to compile by adding this:

#if defined(LIBRETINY)
#include "wiring_math.cpp"
#endif

[thewhobox]

Strange. I tested it locally.

[Phil1pp]

I replaced randomSeed with srandom and now it works.