Sketch names starting with a digit are now allowed

Fix #6592

Author: cmaglie

app/src/processing/app/SketchController.java

@@ -826,8 +826,7 @@ private static String checkName(String origName) {
     if (!newName.equals(origName)) {
       String msg =
         tr("The sketch name had to be modified. Sketch names can only consist\n" +
-          "of ASCII characters and numbers (but cannot start with a number).\n" +
-          "They should also be less than 64 characters long.");
+          "of ASCII characters and numbers and be less than 64 characters long.");
       System.out.println(msg);
     }
     return newName;

arduino-core/src/processing/app/BaseNoGui.java

@@ -873,10 +873,6 @@ static public String sanitizeName(String origName) {
     char c[] = origName.toCharArray();
     StringBuffer buffer = new StringBuffer();
 
-    // can't lead with a digit, so start with an underscore
-    if ((c[0] >= '0') && (c[0] <= '9')) {
-      buffer.append('_');
-    }
     for (int i = 0; i < c.length; i++) {
       if (((c[i] >= '0') && (c[i] <= '9')) ||
           ((c[i] >= 'a') && (c[i] <= 'z')) ||

build/shared/revisions.txt

@@ -10,6 +10,7 @@ ARDUINO 1.8.4
 * Make Preference window fit 600px height displays
 * Fix error when renaming an unsaved, newly added file. Thanks @matthijskooijman
 * Added the ability to increase/decrease font size via keyboard + mouse shortcuts (Ctrl + MouseWheel)
+* Sketch names starting with a digit are now allowed
 
 [libraries]
 * Fixed wrong folder name for "Adafruit Circuit Playground" library, now it can be updated cleanly.