Add test application; fix linking issues with it

SConstruct

@@ -8,19 +8,25 @@ env.Append(CCFLAGS=["-Wall", "-Wextra", "-Werror", "-pedantic"])
 env.Append(CPPPATH=['cpp/', 'include/'])
 
 # Build the library
-env.SharedLibrary('lib/ged', Glob('cpp/*.cpp'))
+gedeng = env.SharedLibrary('lib/gedeng', Glob('cpp/*.cpp'))
+env.Install('test/bin/lib/', gedeng)
 
-# Build the test libraries
+# Test environment setup
 testEnv = Environment(tools=['default', 'compilation_db'])
 testEnv.CompilationDatabase()
 
 testEnv.Append(CCFLAGS=["-Wall", "-Wextra", "-Werror", "-pedantic"])
-testEnv.Append(CPPPATH=['test/', 'include/'])
+testEnv.Append(CPPPATH=['include/', 'test/'])
 testEnv.Append(LIBPATH=['lib/'])
-testEnv.Append(LIBS=['ged'])
+testEnv.Append(LIBS=['gedeng'])
 
-testEnv.Append(CCFLAGS=["-Wall", "-Wextra", "-Werror", "-pedantic"])
+# Make the test executables search for the gedeng lib in their ./lib folder
+testEnv.Append(LINKFLAGS=[
+    '-Wl,--disable-new-dtags,-rpath,\'$$ORIGIN/lib/\''
+])
 
 # Build the test programs
 catch_cpp = "test/catch_amalgamated.cpp"
-testEnv.Program('test/bin/vector-test.out', [catch_cpp, 'test/vector-test.cpp'])
+testEnv.Program('test/bin/vector-test.out', [catch_cpp, 'test/vector/vector-test.cpp'])
+
+testEnv.Program('test/bin/test-app.out', Glob('test/test-app/*.cpp'))

include/Gedeng/Application.h

@@ -3,6 +3,7 @@
 namespace Gedeng {
 
 class Application {
+  public:
     Application() = default;
 
     // Virtual since this class will be inherited by user-created applications

test/test-app/main.cpp

@@ -0,0 +1,16 @@
+#include <Gedeng.h>
+
+class TestApp : public Gedeng::Application {
+  public:
+    TestApp() = default;
+
+    ~TestApp() = default;
+};
+
+int main() {
+    TestApp *app = new TestApp();
+
+    app->run();
+
+    delete app;
+}