in format version 1, entries is the number of entries in the file

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
move save and load methods in VertexObject

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
move the parsing of lines inside VertexObject

Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>