Internal guider improvements

Made a bunch of changes to the internal guider

Applies to all algorithms

• add backlash to calibration plot (guide.cpp, guideinterface.h, internalguider.cpp)
• calibration plot defaults to 20x20" (guide.cpp)
• adjust ui for drift graph: zoom only in Y, X range 120s. (guide.cpp)
• fixed the "guide-distance" entry in the phdlogview-style guide logging (gmath.cpp)
• fixed bad enum usage IN vs OUT for calibration plot (internalguider.cpp, guide.cpp)
• make backlash in calibration optional--UI checkbox (internalguider.cpp, opscalibration.ui, kstars.kcfg)
• Improved issue where backlash in calibration led to calibration not returning to start point (internalguider.cpp)
• Cut short the outward RA and DEC calibration phases, and the DEC backlash movement, if they've already moved sufficiently. Made this 15 pixels, could move to an user-adjustable parameter in the future. (internalguider.cpp/h)

Just applies to SEP MultiStar

• guideview for multistar adds a little + at detection spot for guidestar and each neighbor (guideview.cpp/h, guidestars.cpp)
• removed unnecessary guidestarneighbors class variable (guidestars.cpp/h starcorrespondence.h)
• adjusted multistar guide-star selection logic: reduced emphasis stars with SNR>100, discouraged stars with close neighbors, (guidestars.cpp/h)
• update tests for guide-star-selection changes (testguidestars.cpp)
• changed the SEP MultiStar deblend mincont detection parameter, improved guide-star tracking (guidestars.cpp)
• fixed potential issue with 0 neighbor stars (guidestars.cpp, starcorrespondence.cpp/h
• Improved issue where switching to SEP MultiStar while guiding led to odd results (internalguider.cpp)
• Improved issue where switching out of SEP MultiStar kept neighbors on display (internalguider.cpp, guide.cpp)
• Changed algorithm name from "SEP Multi Star" to "SEP MultiStar (experimental)" (opsguide.ui)
• Debug-log cleanup (guidestars.cpp, starcorrespondence.cpp)