Make new CheckVer & GetEN compatible with linux (#195)

Fixes issues for linux that came from PR #167 

---

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include/Security/Init.h

@@ -7,7 +7,7 @@
 #pragma once
 #include <string>
 void PreGame(const beammp_fs_string& GamePath);
-std::string CheckVer(const beammp_fs_string& path);
+std::string CheckVer(const std::filesystem::path& path);
 void InitGame(const beammp_fs_string& Dir);
 beammp_fs_string GetGameDir();
 void LegitimacyCheck();

src/Security/BeamNG.cpp

@@ -232,9 +232,9 @@ void LegitimacyCheck() {
     }
 #endif
 }
-std::string CheckVer(const beammp_fs_string& dir) {
+std::string CheckVer(const std::filesystem::path& dir) {
     std::string temp;
-    beammp_fs_string Path = dir + beammp_wide("\\integrity.json");
+    std::filesystem::path Path = dir / beammp_wide("integrity.json");
     std::ifstream f(Path.c_str(), std::ios::binary);
     int Size = int(std::filesystem::file_size(Path));
     std::string vec(Size, 0);

src/Startup.cpp

@@ -73,7 +73,11 @@ Version::Version(const std::array<uint8_t, 3>& v)
 }
 
 beammp_fs_string GetEN() {
-    return beammp_wide("BeamMP-Launcher.exe");
+#if defined(_WIN32)
+    return L"BeamMP-Launcher.exe";
+#elif defined(__linux__)
+    return "BeamMP-Launcher";
+#endif
 }
 
 std::string GetVer() {