[Refactor] Replace `rt.util.string.uintToString` with `*ToTempString` functions.

New interface is safer. Also it fixes bug in `_d_arraycopy` where buffer was too small for 64 bit `size_t`.
Add `rt.util.array` which replaces manual checks in functions.

New interface is safer. Also it fixes bug in `_d_arrayctor` which didn't check for array overlap.
Add issue 11461 workaround.

Issue URL: https://d.puremagic.com/issues/show_bug.cgi?id=11461
Fix Issue 8650 - SLice opOpAssign SLice with overlap does not throw

Issue URL: http://d.puremagic.com/issues/show_bug.cgi?id=8650
Fix `Throwable.toString` delegate type as `scope` is required.
Merge pull request #661 from denis-sh/add-more-utils

Add more utils