Fix inability to set negative defaults for integer fields
Tests for same
Merge pull request #43 from mDialog/parser_fixes

Fix inability to set negative defaults for integer fields
Fix parsing properly; -ve floats now work too.
Added a check for an invalid specified import directory.
Merge remote-tracking branch 'origin/master'
Merge pull request #44 from mDialog/fix

Fix parsing properly; -ve float defaults parse correctly
Fixed default values for optional floats. Fixed simple.proto tag number.