When using `git` aliases, the alias would be highlighted red by
fast-syntax-highlighting even though the alias is valid so remove it and
go back to zsh-syntax-highlighting instead.
Tips from [zsh-vimto](https://github.com/laurenkt/zsh-vimto).
* Remove delay when changing mode
* Enable backspace when returning to viins from vicmd mode
macOS is obnoxious and overwrites the PATH from a users ~/.zshenv, which is
sourced first, in /etc/zprofile by calling `/usr/libexec/path_helper -s` so
this is required so that PATH is once again set to the desired value.
* `build` is an alias which on first use invokes `build-dir --build` to
select a build directory, reconfigure the `build` alias, and invoke
the `build` alias on the selected build directory.
* `debug` is an alias to the installed system native debugger.
* `build-dir` is a function to select a build directory by reconfiguring
the `build` alias, it detects `build.ninja` or `Makefile` in the build
directory and selects the appropriate `ninja` or `make` command.
Depends on the `build-dir.py` Python script which uses the `pick`
package to interactively select the build directory.
* `build-run` is a function which builds the specified target then
attempts to run it, making the assumption it resides in the `bin`
subdirectory of the build directory.
* `build-debug` is a function which build the specified tared then
attempts to debug it using the system native debugger, making the
assumption it resides in the `bin` subdirectory of the build
directory.
Add ccache symlink directory to start of PATH, this must be after
`typeset -U PATH` because on macOS this reorders the list so ccache's
symlinks will no longer be at the start of PATH rendering it unusable.
From experimenting `unsetopt flow_control` seems to only disable flow
control for Zsh itself, not for child processes like Vim. To fix the
issue also call `stty -ixon` to disable flow control completely.
Fixes#8
