version2.0.

bug fixed:
plot from standard input raised an error caused by misdefinition of temporary file used to
store the std.input. The wrong definition as caused by improper reference to tmp directory
(/tmp rather /tmp/). Fixed by direct definition of /tmp/ directory. This is used in two points
only in version2.0: i) in the function get_temp_file to open a temporary file, ii) to redirect
std.in to temp file.