bash_aliases: add new functions

- Switch removedupes from an alias to a function
  (now you only need to specify the input and output file)

- Add a computerinfo function that gives you info about your machine

- Change cd function to pd and fix some issues
gitconfig: Add new aliases and improve existing

- Replace 'fixcommit' and 'amend' aliases with 'rewrite-commit-msg'
  which is a lot more clear. Also improve the comments for it.

- New alias 'add-to-last-commit'
  Use when you have changes that you want to add to the previous commit.

- New alias 'undo'
  Discards all new changes.

- New alias 'aliases'
  A human readable version of 'alias'

- Remove alias 'fresh'

- Fix alias 'overwrite'
  Wasn't working as intended.

- New alias 'new-commits'
  Shows the new commits since the last command
vimrc: Be more specific in "set ruler" explanation