Now uses MAX_LINE_BUFFER_SIZE constant for the array sizing of the buffer that hold...

Now uses MAX_LINE_BUFFER_SIZE constant for the array sizing of the buffer that hold lines read in
Now checks that the line being read in does not exceed MAX_LINE_BUFFER_SIZE length, avoiding a crash whenever a long line is read in from a .tex file.  An error is now generated if the line is too long, and line line is truncated at MAX_LINE_BUFFER_SIZE characters.
All error messages are now constructed with wxStrings rather than char arrays.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@8989 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775