Create dotenv readEnvFile single function

Readme.md

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+# dotenv: readEnvFile()
+
+A single function implementation of https://github.com/vlucas/phpdotenv
+
+This is not a functional replacement, but a very simple implementation of the basic functions.
+
+## How it works
+
+Put the function where it is needed or put it in a file and load it.
+
+if not parameter is given it will use `__DIR__` as base path.
+Second parameter is file name override. Default is `.env`
+
+Data is loaded into _ENV only.
+
+If there is already an entry in _ENV then it will not be overwritten.
+
+## .env file example
+
+A valid entry has to start with an alphanumeric string, underscores are allowed and
+then have an equal sign (=). After the equal sign the data block starts. Data can be
+quoted with double quotes (") and if this is done can stretch over multiple lines.
+The openeing double quote must be on the same lign as the requal sign (=). If double
+quoted (") charcters are used it will read each line until another double quote (")
+character is found. Everything after that is ignored.
+
+Any spaces before the variable or before and after the equal sign (=) are ignored.
+
+Line is read until `PHP_EOL`. So any trailing spaces are read too.
+
+Any line that is not valid is ignored.
+
+```ini
+# this line is ignored
+SOMETHING=A
+OTHER="A B C"
+MULTI_LINE="1 2 3
+4 5 6
+7 8 9" ; and this is ignored
+ESCAPE="String \" inside \" other "
+DOUBLE="I will be used"
+DOUBLE="This will be ignored"
+```