Rename project file to "project.godot"

Slimmed down variant from the reverted #8375.
The rationale behind the name change is to give Godot's project file a unique
extension (".godot") that can be registered on the OS to be associated with
the Godot binary (OS registration not implemented here).

This PR also adds the possibility to start the game or editor if launched
with the project.godot passed as argument, which paves the way for allowing
a similar behaviour on a double-click in the OS file manager (code originally
by @Hinsbart).

Closes #6915.

1 files changed, 9 insertions, 9 deletions

diff --git a/core/variant_parser.cpp b/core/variant_parser.cpp
index 5e12b230be..234156d39f 100644
--- a/core/variant_parser.cpp
+++ b/core/variant_parser.cpp
@@ -409,7 +409,7 @@ Error VariantParser::_parse_enginecfg(Stream *p_stream, Vector<String> &strings,
 	Token token;
 	get_token(p_stream, token, line, r_err_str);
 	if (token.type != TK_PARENTHESIS_OPEN) {
-		r_err_str = "Expected '(' in old-style godot.cfg construct";
+		r_err_str = "Expected '(' in old-style project.godot construct";
 		return ERR_PARSE_ERROR;
 	}
 
@@ -420,7 +420,7 @@ Error VariantParser::_parse_enginecfg(Stream *p_stream, Vector<String> &strings,
 		CharType c = p_stream->get_char();
 
 		if (p_stream->is_eof()) {
-			r_err_str = "Unexpected EOF while parsing old-style godot.cfg construct";
+			r_err_str = "Unexpected EOF while parsing old-style project.godot construct";
 			return ERR_PARSE_ERROR;
 		}
 
@@ -1273,7 +1273,7 @@ Error VariantParser::parse_value(Token &token, Variant &value, Stream *p_stream,
 			value = arr;
 
 			return OK;
-		} else if (id == "key") { // compatibility with godot.cfg
+		} else if (id == "key") { // compatibility with project.godot
 
 			Vector<String> params;
 			Error err = _parse_enginecfg(p_stream, params, line, r_err_str);
@@ -1309,7 +1309,7 @@ Error VariantParser::parse_value(Token &token, Variant &value, Stream *p_stream,
 			value = ie;
 			return OK;
 
-		} else if (id == "mbutton") { // compatibility with godot.cfg
+		} else if (id == "mbutton") { // compatibility with project.godot
 
 			Vector<String> params;
 			Error err = _parse_enginecfg(p_stream, params, line, r_err_str);
@@ -1324,7 +1324,7 @@ Error VariantParser::parse_value(Token &token, Variant &value, Stream *p_stream,
 
 			value = ie;
 			return OK;
-		} else if (id == "jbutton") { // compatibility with godot.cfg
+		} else if (id == "jbutton") { // compatibility with project.godot
 
 			Vector<String> params;
 			Error err = _parse_enginecfg(p_stream, params, line, r_err_str);
@@ -1339,7 +1339,7 @@ Error VariantParser::parse_value(Token &token, Variant &value, Stream *p_stream,
 			value = ie;
 
 			return OK;
-		} else if (id == "jaxis") { // compatibility with godot.cfg
+		} else if (id == "jaxis") { // compatibility with project.godot
 
 			Vector<String> params;
 			Error err = _parse_enginecfg(p_stream, params, line, r_err_str);
@@ -1357,19 +1357,19 @@ Error VariantParser::parse_value(Token &token, Variant &value, Stream *p_stream,
 			value = ie;
 
 			return OK;
-		} else if (id == "img") { // compatibility with godot.cfg
+		} else if (id == "img") { // compatibility with project.godot
 
 			Token token; // FIXME: no need for this declaration? the first argument in line 509 is a Token& token.
 			get_token(p_stream, token, line, r_err_str);
 			if (token.type != TK_PARENTHESIS_OPEN) {
-				r_err_str = "Expected '(' in old-style godot.cfg construct";
+				r_err_str = "Expected '(' in old-style project.godot construct";
 				return ERR_PARSE_ERROR;
 			}
 
 			while (true) {
 				CharType c = p_stream->get_char();
 				if (p_stream->is_eof()) {
-					r_err_str = "Unexpected EOF in old style godot.cfg img()";
+					r_err_str = "Unexpected EOF in old style project.godot img()";
 					return ERR_PARSE_ERROR;
 				}
 				if (c == ')')