Reimplement SD.h write methods exactly in File (#5861)

* Reimplement SD.h write methods exactly in File

Replace the individual override with the existing SD.h File's
implementation for all methods of File::write.

Fixes #5846

* Add add'l tests

* Fix Print and File incompatible writes w/casts

Print and File have ambiguous resolutions for single-argument
write(0)s.

Fix by adding explicit methods.  A write of any integer will not be a
const char* write (i.e. won't write a string) but will instead just
write the integer truncated to 8 bits (as makes sense).

* Use 256byte chunks in ::write template

Reduce stack requirements for templated writes to 256bytes, matching the
size uses in WiFiClient/etc. (from 512bytes).  Reduces the chance of
stack overflow.

* Move write(int) methods up to Print.h

Remove some technical debt by moving the ::write(int/short/long) methods
out of FS and HardwareSerial and up into Print.h.

cores/esp8266/FS.h

@@ -80,7 +80,29 @@ public:
     bool isDirectory() const;
 
     // Arduino "class SD" methods for compatibility
-    size_t write(const char *str) { return write((const uint8_t*)str, strlen(str)); }
+    template<typename T> size_t write(T &src){
+      uint8_t obuf[256];
+      size_t doneLen = 0;
+      size_t sentLen;
+      int i;
+
+      while (src.available() > sizeof(obuf)){
+        src.read(obuf, sizeof(obuf));
+        sentLen = write(obuf, sizeof(obuf));
+        doneLen = doneLen + sentLen;
+        if(sentLen != sizeof(obuf)){
+          return doneLen;
+        }
+      }
+
+      size_t leftLen = src.available();
+      src.read(obuf, leftLen);
+      sentLen = write(obuf, leftLen);
+      doneLen = doneLen + sentLen;
+      return doneLen;
+    }
+    using Print::write;
+
     void rewindDirectory();
     File openNextFile();
 

cores/esp8266/HardwareSerial.h

@@ -152,22 +152,6 @@ public:
     {
         return uart_write_char(_uart, c);
     }
-    inline size_t write(unsigned long n)
-    {
-        return write((uint8_t) n);
-    }
-    inline size_t write(long n)
-    {
-        return write((uint8_t) n);
-    }
-    inline size_t write(unsigned int n)
-    {
-        return write((uint8_t) n);
-    }
-    inline size_t write(int n)
-    {
-        return write((uint8_t) n);
-    }
     size_t write(const uint8_t *buffer, size_t size) override
     {
         return uart_write(_uart, (const char*)buffer, size);

cores/esp8266/Print.h

@@ -62,6 +62,13 @@ class Print {
         size_t write(const char *buffer, size_t size) {
             return write((const uint8_t *) buffer, size);
         }
+        // These handle ambiguity for write(0) case, because (0) can be a pointer or an integer
+        size_t write(short t) { return write((uint8_t)t); }
+        size_t write(unsigned short t) { return write((uint8_t)t); }
+        size_t write(int t) { return write((uint8_t)t); }
+        size_t write(unsigned int t) { return write((uint8_t)t); }
+        size_t write(long t) { return write((uint8_t)t); }
+        size_t write(unsigned long t) { return write((uint8_t)t); }
 
         size_t printf(const char * format, ...)  __attribute__ ((format (printf, 2, 3)));
         size_t printf_P(PGM_P format, ...) __attribute__((format(printf, 2, 3)));