fix #6583, fix #14376, index+search now generated for all projects, many bug fixes with nim doc (#14324)

* refs #6583 fix nim doc output
* changelog
* change default for outDir when unspecified
* cleanups
* --project implies --index

testament/lib/stdtest/unittest_light.nim

@@ -1,5 +1,3 @@
-# note: consider merging tests/assert/testhelper.nim here.
-
 proc mismatch*[T](lhs: T, rhs: T): string =
   ## Simplified version of `unittest.require` that satisfies a common use case,
   ## while avoiding pulling too many dependencies. On failure, diagnostic
@@ -31,8 +29,8 @@ proc mismatch*[T](lhs: T, rhs: T): string =
       result.add "lhs[0..<i]:{" & replaceInvisible($lhs[
           0..<i]) & "}"
 
-proc assertEquals*[T](lhs: T, rhs: T) =
+proc assertEquals*[T](lhs: T, rhs: T, msg = "") =
   when false: # can be useful for debugging to see all that's fed to this.
     echo "----" & $lhs
   if lhs!=rhs:
-    doAssert false, mismatch(lhs, rhs)
+    doAssert false, mismatch(lhs, rhs) & "\n" & msg