v2.1.1 - Minor bug fixes

This release fixes several bugs causing crashes or incorrect results.

• Fixed a crash when running without a time limit set
• Fixed cases where the tool wrongly reported "no solution" for networks with transport-only metabolites
• Fixed a crash when the solver returned empty or incomplete output
• Fixed an argument error affecting the seed detection option
• Metabolites needed for biomass production are now correctly proposed as possible seeds, even when their only producer was removed during network cleanup
• seed2lp now gives a clear, actionable error message when the input SBML file predates version 3.x or lacks the Flux Balance Constraints (FBC) package, instead of crashing (#3)
• Fixed an issue where rewriting an SBML file (network command) could produce an invalid file when the source network contained notes or group annotations

Thanks to @csaintmartin for reporting #3.