Update gitignore to ignore idea and vscode

[SethFalco]

I'm about to rebase and respond to your feedback on #114.
Just wanted to propose some minor changes, though.

.gitignore

• Ignores all IntelliJ specific files. (What I was using before, so had some files left around still.)
• Ignores all Visual Studio Code specific files. (What I'm using now.)
• Replaces the dead link at the top of the file.

Edit: While I was at it, I opted to update the contents of .gitignore with the up-to-date revision on github/gitignore.

I can replace the link with https://raw.githubusercontent.com/github/gitignore/6651bca9c83572f908474fc6206ed8a80df91290/Maven.gitignore if preferred?
I prefer the current link, but whatever suits you.

.editorconfig

For those using code editors like Visual Studio Code, it can be easier if the project defines its preferences using EditorConfig to override any program settings. (a vendor-agnostic configuration file that many code editors support)

I've just taken the EditorConfig configuration from the most starred Java project Apache has on GitHub:
https://github.com/apache/dubbo/blob/3.0/.editorconfig

It could be worth considering if you'd want to change anything about it, for example I think something like this might be better:

root = true

[*]
indent_style = space
indent_size = 2
end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true

# Preserve line breaks in Markdown
[*.md]
trim_trailing_whitespace = false

# 4 space indentation
[*.{java,xml}]
indent_size = 4

[coveralls]

Coverage remained the same at 98.31% when pulling 4f442ba on SethFalco:chores into 46bae4b on apache:master.

[garydgregory]

We don't use editorconfig anywhere in Commons that I'm aware of so let's skip it. If anything , we could store formatting configs for Eclipse, IJ, and so on in src/conf, maybe...

[SethFalco]

Just made one more minor edit, sorry!
About to look at my PRs to commons-beanutils again since I left those hanging. ^-^'

Realized the IntelliJ/Eclipse files can be in submodule directories as well. Thought I should update that too.