add timeout to streamSkipUntil

src/TinyGsmClientA6.h

@@ -644,9 +644,13 @@ public:
     streamWrite(tail...);
   }
 
-  bool streamSkipUntil(char c) { //TODO: timeout
-    while (true) {
-      while (!stream.available()) { TINY_GSM_YIELD(); }
+  bool streamSkipUntil(char c) {
+    const unsigned long timeout = 1000L;
+    unsigned long startMillis = millis();
+    while (millis() - startMillis < timeout) {
+      while (millis() - startMillis < timeout && !stream.available()) {
+        TINY_GSM_YIELD();
+      }
       if (stream.read() == c)
         return true;
     }

src/TinyGsmClientESP8266.h

@@ -412,9 +412,13 @@ public:
     streamWrite(tail...);
   }
 
-  bool streamSkipUntil(char c) { //TODO: timeout
-    while (true) {
-      while (!stream.available()) { TINY_GSM_YIELD(); }
+  bool streamSkipUntil(char c) {
+    const unsigned long timeout = 1000L;
+    unsigned long startMillis = millis();
+    while (millis() - startMillis < timeout) {
+      while (millis() - startMillis < timeout && !stream.available()) {
+        TINY_GSM_YIELD();
+      }
       if (stream.read() == c)
         return true;
     }

src/TinyGsmClientM590.h

@@ -589,9 +589,13 @@ public:
     streamWrite(tail...);
   }
 
-  bool streamSkipUntil(char c) { //TODO: timeout
-    while (true) {
-      while (!stream.available()) { TINY_GSM_YIELD(); }
+  bool streamSkipUntil(char c) {
+    const unsigned long timeout = 1000L;
+    unsigned long startMillis = millis();
+    while (millis() - startMillis < timeout) {
+      while (millis() - startMillis < timeout && !stream.available()) {
+        TINY_GSM_YIELD();
+      }
       if (stream.read() == c)
         return true;
     }

src/TinyGsmClientSIM800.h

@@ -837,9 +837,13 @@ public:
     streamWrite(tail...);
   }
 
-  bool streamSkipUntil(char c) { //TODO: timeout
-    while (true) {
-      while (!stream.available()) { TINY_GSM_YIELD(); }
+  bool streamSkipUntil(char c) {
+    const unsigned long timeout = 1000L;
+    unsigned long startMillis = millis();
+    while (millis() - startMillis < timeout) {
+      while (millis() - startMillis < timeout && !stream.available()) {
+        TINY_GSM_YIELD();
+      }
       if (stream.read() == c)
         return true;
     }

src/TinyGsmClientU201.h

@@ -606,9 +606,13 @@ public:
     streamWrite(tail...);
   }
 
-  bool streamSkipUntil(char c) { //TODO: timeout
-    while (true) {
-      while (!stream.available()) { TINY_GSM_YIELD(); }
+  bool streamSkipUntil(char c) {
+    const unsigned long timeout = 1000L;
+    unsigned long startMillis = millis();
+    while (millis() - startMillis < timeout) {
+      while (millis() - startMillis < timeout && !stream.available()) {
+        TINY_GSM_YIELD();
+      }
       if (stream.read() == c)
         return true;
     }