Optimize GDBObjPolyFaceMesh.FormatEntity - use integer-based edge tracking

[konard]

Summary

Optimized GDBObjPolyFaceMesh.FormatEntity procedure to significantly improve rendering performance of PolyFaceMesh entities.

Problem

The original implementation had several performance issues:

• Used string-based edge tracking with linear search (O(n²) complexity)
• Repeated IntToStr conversions for each edge comparison
• Frequent SetLength calls growing array one element at a time
• Excessive code duplication

Solution

Key optimizations implemented:

1. Integer-based edge tracking - Replaced string keys with integer comparisons
2. Pre-allocation - Allocate edge array based on face count (max 4 edges per face)
3. Vertex count caching - Store VertexArrayInWCS.Count to avoid repeated calls
4. Early exit - Added check for empty meshes (vertexCount < 2)
5. Code reduction - Reduced from ~620 lines to ~350 lines

Performance Improvements

• Eliminated expensive string operations (IntToStr, string concatenation)
• Reduced memory allocations by pre-allocating array with 256-element chunks
• Simplified duplicate edge detection with direct integer comparison
• Maintained correct wireframe rendering according to DXF Polyface Mesh specification

Testing

The algorithm maintains the same rendering logic:

• Triangle faces: edges (v1-v2), (v2-v3), (v3-v1)
• Quad faces: edges (v1-v2), (v2-v3), (v3-v4), (v4-v1)
• Edge visibility based on positive vertex indices
• Duplicate edge elimination

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Issue: #760