Fix coverity issues (medium)
This MR fixes several medium-level issues found by Coverity Scan.
While less serious, medium-level issues are sometimes slightly more complex to fix because of code intent, and thus more prone to regressions than high-level issues.
Issues in SEP were set to ignore. Some issues set to ignore based on code intent. CID1445705 - unchecked cast in details table. CID1445707 - unchecked fread returned bytes in StarComponent. CID1445708 - unchecked cast in guider interface. CID1445711 - unchecked cast in observing list. CID1445714 - unchecked cast in details dialog. CID1445719 - unchecked cast in details dialog. CID1445721 - uninit var hfr in Analyze capture session. CID1445725 - unchecked cast in EkosLive message. CID1445726 - dead duplicated code in FITS packer. CID1445728 - possible division by zero in Scheduler job time estimation. CID1445729 - uninit var in Linear Focus. CID1445730 - unchecked cast in EkosLive message. CID1445734 - uninit vars in SchedulerJob. CID1445742 - unintended sign extension in FITS star filtering. CID1445743 - unchecked cast in EkosLive message. CID1445748 - uninit vars in Meridian Flip test. CID1445753 - stray semicolon in Capture test helper macro. CID1445757 - fix if construct (sorry Akarsh).