Change history alias into a function

This commit changes the history alias into a function which puts
the passed arguments before `-l 1`. It also provides a temporary
workaround to the lack of a `history -c` command in zsh.
This resolves #739 and resolves #789.
Simplify `if' into oneliner, allow spaces in HISTFILE
Put completion initialization at the top

This is necessary to enable setting completion stuff in library
scripts.
Organize history.zsh file and improve comments
Merge branch 'run-compinit-first' into fix-history-alias-beta
Use `fc' completion for fn_history and history alias

Needs to have compinit loaded before lib/ files (check out
branch `run-compinit-first')
Merge branch 'fix-history-alias-beta' into dev