Sections' and Sessions' sort order cannot be influenced

[MrCsabaToth]

The Sections and Sessions right now are listed in the order they were entered. There should be a way to change that order.

Expected Behavior

To have some kind of a way to change the order of sessions and sections.

Current Behavior

The Sections and Sessions right now are listed in the order they were entered.

Possible Solution

Either explicitly manually set a rank variable (just like for sponsor levels), or at some later point we can introduce some list widget which allows ordering by drag & drop on the UI?

Steps to Reproduce

1. Add a new Section. It will be added to the end.
2. Add a new Session within a Section. It will be added to the end of the Section.

Detailed Description

Normally we'd want to list the sessions grouped by location and sorted by time within that location. The time is currently a free text entry, so it's easier to rely on an explicit rank field, and that will allow more flexibility than an assumed ordering/grouping.

Possible Implementation

Add a rank field to both Section and Session.
Allow the entry and edition of that value, and later maybe even GUI drag & drop order list widget editing at some point in the future.

[MrCsabaToth]

[neojato]

@MrCsabaToth I plan on testing your PR tonight and will merge asap.

[MrCsabaToth]

No rush! (the cat suggests otherwise, but no rush)

[MrCsabaToth]

PR #31 resolves this