Properly handle staticExec() generating large output.

A staticExec() invocation that generated more than the internal
buffer size worth of output blocked because the compiler waited
for the process to terminate before reading the output.
Merge pull request #1524 from rbehrends/fix-staticexec2

Properly handle staticExec() generating large output.
fixes #1444
minor bugfix for void .compileTime procs
fixes #1511
fixes #903, fixess #1513
Threads work again
fixes #1366
mostly fixes #1339
fixes #1067
fixes #665
manual merge of #1526