2nd try at pull #2205
Replace 0 with NULL
Make implicit cast from long double to integer explicit
Merge pull request #2214 from yebblies/zeronull

[DDMD] Replace 0 with NULL
Merge pull request #2213 from yebblies/floatint

[DDMD] Make implicit cast from long double to integer explicit
Merge pull request #2212 from WalterBright/refactor_error_check2

2nd try at pull #2205