Fix MicTX gain when using decimal values

Fix draw bearing

Fixed bug in datetime

As shown in https://github.com/eried/portapack-mayhem/issues/88 ...

Tiny bug but probably responsible for badly forming datetime in several apps, as it is used in ACARS, POCSAG and ADSB_TX (and of course AIS RX)

New Antenna length Calculator

It reads the antennas definition from a txt file:

WHIPCALC/ANTENNAS.TXT

Inside the textfile you place each antenna you own with the following sintaxis:

<antenna label> <elements length in mm, separated by a space>

For example:

ANT500 185 315 450 586 724 862

Input the required frequency, adjust the wave type (full / half / quarter, etc.) and the calculator will return the antenna length (metric and imperial) while also calculating how much you need to expand the fitting antennas you got defined on the txt.

It may return up to 8 matching antennas, which is more than enough (normally you will have 2, perhaps 3 telescopic antennas around for your portapack)

If by any chance your antennas txt got more than 8 antennas, and more than 8 matches the length of the freq / wave you want, it will only show the first 8 matching antennas and will warn you at the bottom that there are even more results (hidden).

All calculations now are rounded into the best integer, considering first decimal, so precision is double than the original antenna calculator app.