logic: fixed environment variable detection

* fixed detection of environment variables in path that are encapsulated in %VARIABLE_NAME%
* mentioned notation for environment variables in documentation

src/lib/utility/file/FilePath.cpp

@@ -121,11 +121,11 @@ FilePath FilePath::expandEnvironmentVariables() const
 {
 	std::string text = str();
 
-	static std::regex env("\\$\\{([^}]+)\\}|%([0-9A-Za-z\\/]*)%");
+	static std::regex env("\\$\\{([^}]+)\\}|%([^%]+)%"); // ${VARIABLE_NAME} or %VARIABLE_NAME%
 	std::smatch match;
 	while (std::regex_search(text, match, env))
 	{
-		const char * s = getenv(match[1].str().c_str());
+		const char * s = match[1].matched ? getenv(match[1].str().c_str()) : getenv(match[2].str().c_str());
 		if (s == nullptr)
 		{
 			LOG_ERROR(match[1].str() + " is no a environment variable");

web/documentation/index.html

@@ -558,6 +558,8 @@
 
 					<h3>Path List Box</h3>
 					<p>The Path List Box is a user interface element that is used within the <a href="#PreferencesWindow">Preferences Window</a>  and the <a href="#ProjectSetupWizard">Project Setup Wizard</a>. It allows for entering a list of file and directory paths.</p>
+					<p>If you want to use environment variables you can use either of the following notations.</p>
+					<pre>${VARIABLE_NAME} or %VARIABLE_NAME%</pre>
 					<div class="row">
 						<div class="col-sm-10 col-sm-offset-1">
 							<img src="img/path_list_box.png" style="width:100%;">