guess how much memory will be needed and adjust chunk size
reboot hpohl's #2470
[trivial] Fix warning in cast.c
fix Issue 13088 - Compiler segfaults with trivial case code
fix Issue 13087 - Error: no property 'xyz' for type 'Vec!4'
Merge pull request #3613 from WalterBright/hpohl-opt

Increase allocation chunk size + minor refactoring
Merge pull request #3736 from 9rnsr/fix13087

[REG2.066a] Issue 13087 - Error: no property 'xyz' for type 'Vec!4'
fix Issue 13089 - Spurious 'is not nothrow' error on static array initialization