Loads properties from the specified Reader.
The properties file is interpreted according to the following rules:
Empty lines are ignored.
Lines starting with either a "#" or a "!" are comment lines and are
ignored.
A backslash at the end of the line escapes the following newline
character ("\r", "\n", "\r\n"). If there's whitespace after the
backslash it will just escape that whitespace instead of concatenating
the lines. This does not apply to comment lines.
A property line consists of the key, the space between the key and
the value, and the value. The key goes up to the first whitespace, "=" or
":" that is not escaped. The space between the key and the value contains
either one whitespace, one "=" or one ":" and any amount of additional
whitespace before and after that character. The value starts with the
first character after the space between the key and the value.
Following escape sequences are recognized: "\ ", "\\", "\r", "\n",
"\!", "\#", "\t", "\b", "\f", and "\uXXXX" (unicode character).