Fix v0.4.1rc3 Enhances Iterators and Stability

Version v0.4.1rc3 fixes key issues by @charles-cooper, including gas usage of iterators (#4485) and caching iterator eval results (#4488). It defines rounding mode for sqrt (#4486) and disables augassign with overlap (#4487). The build tool OS rollback (#4494) improves stability. Full changelog covers v0.4.1rc2 to v0.4.1rc3 updates.