Interaction between markdown blockquotes and sections

After review better determination of Atx header.

Solved some corner cases as well
```
> text
##NO header

##Second test on no header
```

and
```
> text
 ## text
```

Author: albert-github

src/markdown.cpp

@@ -153,6 +153,7 @@ struct Markdown::Private
       const QCString &link, const QCString &attributes,
       const FileDef *fd);
   int isHeaderline(std::string_view data, bool allowAdjustLevel);
+  int isAtxHeaderLevel(std::string_view data, size_t &i);
   int isAtxHeader(std::string_view data, QCString &header,QCString &id,bool allowAdjustLevel,
       bool *pIsIdGenerated=nullptr);
   void writeOneLineHeaderOrRuler(std::string_view data);
@@ -2028,16 +2029,11 @@ QCString Markdown::Private::extractTitleId(QCString &title, int level, bool *pIs
   return "";
 }
 
-
-int Markdown::Private::isAtxHeader(std::string_view data,
-                       QCString &header,QCString &id,bool allowAdjustLevel,bool *pIsIdGenerated)
+// find start of header text and determine heading level
+int Markdown::Private::isAtxHeaderLevel (std::string_view data, size_t &i)
 {
-  AUTO_TRACE("data='{}' header={} id={} allowAdjustLevel={}",Trace::trunc(data),Trace::trunc(header),id,allowAdjustLevel);
-  size_t i = 0;
-  int level = 0, blanks=0;
   const size_t size = data.size();
-
-  // find start of header text and determine heading level
+  int level = 0, blanks=0;
   while (i<size && data[i]==' ') i++;
   if (i>=size || data[i]!='#')
   {
@@ -2049,11 +2045,24 @@ int Markdown::Private::isAtxHeader(std::string_view data,
     return 0;
   }
   while (i<size && data[i]==' ') i++,blanks++;
-  if (level==1 && blanks==0)
+  if (level>=1 && blanks==0)
   {
     return 0; // special case to prevent #someid seen as a header (see bug 671395)
   }
 
+  return level;
+}
+
+int Markdown::Private::isAtxHeader(std::string_view data,
+                       QCString &header,QCString &id,bool allowAdjustLevel,bool *pIsIdGenerated)
+{
+  AUTO_TRACE("data='{}' header={} id={} allowAdjustLevel={}",Trace::trunc(data),Trace::trunc(header),id,allowAdjustLevel);
+  size_t i = 0;
+  int level = 0;
+  const size_t size = data.size();
+
+  if (!(level = isAtxHeaderLevel(data, i))) return 0;
+
   // find end of header text
   size_t end=i;
   while (end<size && data[end]!='\n') end++;
@@ -2856,7 +2865,8 @@ size_t Markdown::Private::writeBlockQuote(std::string_view data)
       {
         curLevel=level;
         i = indent;
-        if (txt[0] == '#') break; // begin of markdown section command
+        size_t ii = i;
+        if (!isAtxHeaderLevel(data, ii)) break; // begin of markdown section command
         out += txt;
       }
       isGitHubFirst = false;