Convert .ino -> .cpp (#2228)

- general conversion from .ino modules into a separate .cpp files
- clean-up internal headers, place libraries into .h. guard .cpp with _SUPPORT flags 
- fix some instances of shared variables instead of public methods
- tweak build system to still build a single source file via os environment variable ESPURNA_BUILD_SINGLE_SOURCE

code/espurna/ota.cpp

@@ -0,0 +1,79 @@
+/*
+
+OTA MODULE COMMON FUNCTIONS
+
+*/
+
+#include "ota.h"
+#include "system.h"
+#include "terminal.h"
+#include "ws.h"
+
+void otaPrintError() {
+    if (Update.hasError()) {
+        #if TERMINAL_SUPPORT
+            Update.printError(terminalSerial());
+        #elif DEBUG_SERIAL_SUPPORT && defined(DEBUG_PORT)
+            Update.printError(DEBUG_PORT);
+        #endif
+    }
+}
+
+bool otaFinalize(size_t size, int reason, bool evenIfRemaining) {
+    if (Update.isRunning() && Update.end(evenIfRemaining)) {
+        DEBUG_MSG_P(PSTR("[OTA] Success: %7u bytes\n"), size);
+        deferredReset(500, reason);
+        return true;
+    }
+
+    otaPrintError();
+    eepromRotate(true);
+
+    return false;
+}
+
+// Helper methods from UpdaterClass that need to be called manually for async mode,
+// because we are not using Stream interface to feed it data.
+bool otaVerifyHeader(uint8_t* data, size_t len) {
+    if (len < 4) {
+        return false;
+    }
+
+    // ref: https://github.com/esp8266/Arduino/pull/6820
+    // accept gzip, let unpacker figure things out later
+    if (data[0] == 0x1F && data[1] == 0x8B) {
+        return true;
+    }
+
+    // Check for magic byte with a normal .bin
+    if (data[0] != 0xE9) {
+        return false;
+    }
+
+    // Make sure that flash config can be recognized and fit the flash
+    const auto flash_config = ESP.magicFlashChipSize((data[3] & 0xf0) >> 4);
+    if (flash_config && (flash_config > ESP.getFlashChipRealSize())) {
+        return false;
+    }
+
+    return true;
+}
+
+void otaProgress(size_t bytes, size_t each) {
+    // Removed to avoid websocket ping back during upgrade (see #1574)
+    // TODO: implement as separate from debugging message
+    #if WEB_SUPPORT
+        if (wsConnected()) return;
+    #endif
+
+    // Telnet and serial will still output things, but slightly throttled
+    static size_t last = 0;
+    if (bytes < last) {
+        last = 0;
+    }
+
+    if ((bytes > each) && (bytes - each > last)) {
+        DEBUG_MSG_P(PSTR("[OTA] Progress: %7u bytes\r"), bytes);
+        last = bytes;
+    }
+}