Bimonthly Stable INDI Library release introduces new drivers and fixes for existing ones.

Some highlights:
+ Stable Astrotrac Mount driver.
+ Developer build script for UNIX users (#1529)
+ ESATTO Backlash measure and correction (#1526)
+ Correct color space when stacking on indi_v4l2_ccd driver with a web cam that doesn't have color space info. (#1520)
+ The driver for the Planewave Delta-T was not working (#1515)
+ Improved handling of myFP2ESP controllers (#1514)
+ Pegasus UCH (#1513)
+ TheSkyX/Paramount Pier-side + guide async cmd fixes (#1506)
+ Update lx200_OnStep.cpp (#1527)
+ indicom: fix FreeBSD compilation (#1524)