enhancement: support Savestates as a parameter (fixes #1522)

- We can now pass a savestate file (.uss) as a direct parameter to the Amiberry executable, and it will recognize and handle it, without having to use --statefile <filename>
- Added mimetype for savestate files

packaging/linux/mime/amiberry.xml

@@ -34,4 +34,13 @@
         <glob-deleteall/>
         <glob pattern="*.lha"/>
     </mime-type>
+	<mime-type type="application/x-UAE-savestate-file">
+		<comment>UAE SaveState file</comment>
+		<generic-icon name="amiberry"/>
+		<magic-deleteall/>
+		<magic priority="60">
+			<match type="string" value="UAE" offset="16:18"/>
+		</magic>
+		<glob pattern="*.uss"/>
+	</mime-type>
 </mime-info>

src/main.cpp

@@ -1143,6 +1143,21 @@ static void parse_cmdline (int argc, TCHAR **argv)
 				whdload_auto_prefs(&currprefs, txt);
 				SetLastActiveConfig(txt);
 			}
+			else if (_tcscmp(txt2.c_str(), ".uss") == 0)
+			{
+				write_log("Statefile... %s\n", txt);
+				if (my_existsfile2(txt))
+				{
+					savestate_state = STATE_DORESTORE;
+					_tcscpy(savestate_fname, txt);
+				}
+				else
+				{
+					get_savestate_path(savestate_fname, MAX_DPATH - 1);
+					strncat(savestate_fname, txt, MAX_DPATH - 1);
+					savestate_state = STATE_DORESTORE;
+				}
+			}
 			else if (_tcscmp(txt2.c_str(), ".cue") == 0
 				|| _tcscmp(txt2.c_str(), ".iso") == 0
 				|| _tcscmp(txt2.c_str(), ".chd") == 0)