Implement basic serialization / deserialization of OPOSSUM models

Closes #19

See merge request !16

# Conflicts:
#   .gitignore

Resolve "Project name and logo"

Closes #8

See merge request !15

# Conflicts:
#   .gitignore

opticscnery example now exports model file (opticscenery.opm)

Resolve "tests of CLI fail because of "\\" in windows and "/" in linux"

Closes #52

See merge request !14

Edge connections still missing.

Resolve "Create command line tool for analysis"

Closes #36

See merge request !12

nodes and edges are read but grpah is not yet constructed.

Fix clippy warnings.

No node factory method yet

Merge branch '36-create-command-line-tool-for-analysis' of git.gsi.de:phelix/rust/opossum into 36-create-command-line-tool-for-analysis

Merge branch '36-create-command-line-tool-for-analysis' of git.gsi.de:phelix/rust/opossum into 36-create-command-line-tool-for-analysis

Merge branch '36-create-command-line-tool-for-analysis' of git.gsi.de:phelix/rust/opossum into 36-create-command-line-tool-for-analysis

Merge branch '36-create-command-line-tool-for-analysis' of git.gsi.de:phelix/rust/opossum into 36-create-command-line-tool-for-analysis

Merge branch '36-create-command-line-tool-for-analysis' of git.gsi.de:phelix/rust/opossum into 36-create-command-line-tool-for-analysis