FPChecker 0.6.0

• Added FP32 rounding-error tracking (shadow-value style), including improved accumulation across operations and files.
• Added line-granularity reporting for accumulated rounding error, including per-line visualizations in reports.
• Reports high-error hotspots that can help guide mixed-precision and lower-precision tuning decisions.
• Improved reporting outputs: better HTML layout, shell-friendly rounding-error tables, and support for multi-file rounding sections.
• Expanded error-analysis coverage for math functions, floating-point return values/calls, and MPI-related paths.
• Added substantial regression tests for FP32 error analysis and report generation.
• Fixed multiple bugs and memory leaks in analysis and reporting components.