Support for Ubuntu 18.04

[ernstki]

To be clear right up front, Ubuntu 18.04 loses support in April of 2023, so I'm not suggesting you bend yourself all out of shape to support it.

That said, I have patched Seer to build on 18.04, the two major limitations being an older CMake (which I had to change one statement in CMakeLists.txt to accommodate) and older Qt libraries (which I had to do a bunch of #ifdefs to accommodate).

PR #108 represents the necessary fixes. See below for instructions on how to apply the patch from that PR to your own source tree.

@epasveer, feel free to close both this issue and PR #108, because just having this in the issue tracker for posterity is all that I think is necessary.

[ernstki]

Here's how to get the patch file for PR #108 and apply it to your own copy of the code:

cd the/directory/where/you/put/source/code

git clone https://github.com/epasveer/seer.git
cd seer

# get the patch file from PR #108
wget https://github.com/epasveer/seer/pull/108.diff
# if you don't have 'wget' on your system, do this
#curl -LOJ https://github.com/epasveer/seer/pull/108.diff

# apply the patch(es)
patch -p1 <108.diff

# build
cd src/build
cmake ..
make -j4 seergdb

[epasveer]

Hey Kevin.

The changes look good. I'll go ahead an do the pull request in #108

To be honest, I ran into this problem with QString::front()/back() before. I tried to urge people to newer versions of Qt. Even the OpenSuse didn't adopt it til their latest release in February. Supporting the old api for a little while longer can't hurt. :^)

Anyway, thanks for you work! It's mundane task adding those #ifdefs.

[ernstki]

Well, it's kind of a shame to have those #ifdefs all sullying up your actual main branch, but thanks for merging it. It was repetitive, but with the vi keybindings switched on in Qt Creator, it wasn't too bad. :)