fix Issue 10377 - std.typecons.wrap doesn't consider private members
Make conv unittest private simbols private

There were some symbols in a "version(unittest)" block that were not declared private.

This can create some conflicts during unittest releases. I started out just declaring them private, but that created some ambiguities in other modules that used "A" in their names, eg:
```D
struct Appender(A : T[], T)
```

`std\array.d(2129): Error: module std.array std.conv.A is private`.

So I just mangled the names. As a workaround. I'll file a bug report later.
Merge pull request #1349 from monarchdodra/privateConv

Make conv unittest private simbols private
Merge pull request #1350 from 9rnsr/fix10377

Issue 10377 - std.typecons.wrap doesn't consider private members
Issue 10408 - Fix compile error with multiple-function reduce on a const range.
Fix save in filter.

filterBidir was actually correct.
Merge pull request #1363 from monarchdodra/filterSave

Fix save in filter.
Merge pull request #1361 from irritate/issue_10408

Issue 10408 - Fix compile error with multiple-function reduce on a const...
Issue 5692 - Fix printing of complex numbers with a negative imaginary part.
Removes redundant plus sign before the negative sign.
http://d.puremagic.com/issues/show_bug.cgi?id=5692
Merge pull request #1366 from irritate/issue_5692

Issue 5692 - Fix printing of complex numbers with a negative imaginary p...