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

tests/nimdoc/imp.nim

@@ -0,0 +1 @@
+proc fn5*() = discard

tests/nimdoc/m13129.nim

@@ -17,11 +17,9 @@ proc main*() =
     doAssert defined(m13129Foo2)
     doAssert not defined(nimdoc)
     echo "ok2: backend: " & querySetting(backend)
-    # echo defined(c), defined(js), 
 
 import std/compilesettings
 when defined nimdoc:
-  # import std/compilesettings
   static:
     doAssert defined(m13129Foo1)
     doAssert not defined(m13129Foo2)
@@ -33,6 +31,6 @@ when isMainModule:
     let cache = querySetting(nimcacheDir)
     doAssert cache.len > 0
     let app = getAppFilename()
-    doAssert app.isRelativeTo(cache)
+    doAssert app.isRelativeTo(cache), $(app, cache)
     doAssert querySetting(projectFull) == currentSourcePath
     echo "ok3"

tests/nimdoc/sub/imp.nim

@@ -0,0 +1 @@
+proc fn4*() = discard

tests/nimdoc/sub/imp2.nim

@@ -0,0 +1 @@
+proc fn3*() = discard

tests/nimdoc/sub/mmain.nim

@@ -0,0 +1,8 @@
+{.warning[UnusedImport]: off.}
+
+import ../imp as impa
+import imp as impb
+import imp2
+
+proc fn1*() = discard
+proc fn2*() = discard