Replaced perror() calls with an error buffer. Issue #10

[andreondra]

Fixes the issue #10. As @hroncok suggested, any subsequent call will replace the current message without concatenation.

[andreondra]

Changed to WIP until the previous PR is merged.

[hroncok]

It would be easier to me to review chnages in isolation, rather than on top of each other. How's your git-fu wrt branches? Are you able to submit each individual change from a different branch?

[andreondra]

Yes, that's what I plan to do next, I just kinda forgot about it while resolving the first issue. Sorry for a little mess.

[andreondra]

Note: removed irrelevant commits in this PR.

[hroncok]

Basic testing shows this behaves mostly as expected, thanks!

As far as API goes, it would be really nice if I could get the concentrated error message programmatically without printing it to stderr. Imagine this scenarios:

• I develop a GUI and I want to process an STL file. When I open it and an error happens, I want to show the message in a GUI error window.
• I develop Python bindings. When Python code opens the STL file and an error happens I want to include the entire message in the Python exception.

Currently, I can only get the error_buffer part, or print the full error message to stdout.

[hroncok]

As far as API goes, it would be really nice if I could get the concentrated error message programmatically without printing it to stderr. Imagine this scenarios:

• I develop a GUI and I want to process an STL file. When I open it and an error happens, I want to show the message in a GUI error window.
• I develop Python bindings. When Python code opens the STL file and an error happens I want to include the entire message in the Python exception.

Currently, I can only get the error_buffer part, or print the full error message to stdout.

Oh, ignore me, I must have been tired when writing this. The entire error message is stored in the error attribute, as it should be.