Replace tabs with two spaces

[tshort]

Tabs are causing formatting issues on GitHub and in my local editor. This PR is a mass search and replace. There are still inconsistencies with indentation, but this helps.

[ufechner7]

Do you think two spaces is a good choice? I am more used to four spaces.

[tshort]

Most files here use two spaces for indentation. But, there are many tabs sprinkled in several files. Replacing these with two spacings generally keeps the indentation consistent.

(I also prefer four spaces for indentation, but I've worked on repos that used two.)

[ufechner7]

So I wait for the decision of the repo-owner.

[tshort]

Two vs. four vs. something else should be another issue. This should be a noncontroversial cleanup.

[HildingElmqvist]

I made a mistake of merging. There were many errors in the tabs branch. I did not pay enough attention since large diffs are not presented in the github window.

Tom, could you help undo the merge?

[tshort]

I'm sorry about that, @HildingElmqvist. I must have goofed something. If we get Travis set up for CI testing, it'll help avoid this type of thing (we need to register ModiaMath first). We can tell if a PR will mess up the package tests.

I'm not a git or github expert. It looks like you can use GitHub to revert a PR. See here:

https://help.github.com/articles/reverting-a-pull-request/

If that doesn't work, a manual way to do that is to revert a local branch to the last known good version. Then, you can submit that as a PR. It looks like the last good version is 90f52e9.

Git is complicated and confusing, but the good news is that it's hard to lose information, so we should be able to backtrack.

[tshort]

I can also take a look to see if I can fix what I broke. Will look tonight.

[tshort]

Looks like the damage was limited to one file. Working on a PR to fix it now.

[tshort]

FYI, the way I fixed it was to revert the damaged file (in a separate branch):

git checkout -b tabs-to-spaces-fix
git checkout  90f52e97dd08c0f73f48ad6e1f18979e57d6c15f src/symbolic/DAEquations/SymbolicTransform.jl 

I ran the package tests in Julia to make sure they passed. I edited SymbolicTransform.jl to replace tabs with two spaces. Lastly, I committed the change and submitted a PR.