ShapeOut 2.15.4

This is a bug-fix release. Shape-Out will now not override any pre-existing files in the export output directory. (If you are working with two instances of Shape-Out, please still try to not export to the same directory from both). In some cases, Shape-Out could not open input files that were recorded with zero flow. For more details see the changelog below.

• fix: very small numbers not parsed when showing metadata (#158)
• fix: do not allow question mark "?" in exported file names (#156)
• fix: do not override files when exporting data (#153)
• fix: remove the "so2exp" prefix when exporting data (#157)