Re-organize the shells' initialization logic

- unify ~/.config/shell/aliases.sh and ~/.config/shell/utils.sh
  into a common ~/.config/shell/init.sh
- split the contents of ~/.config/shell/aliases.sh
  into the folder ~/.config/shell/aliases.d
- split the contents of ~/.config/shell/utils.sh
  into the folder ~/.config/shell/utils.d

.config/shell/aliases.d/files.sh

@@ -0,0 +1,59 @@
+# Make working with files more convenient
+
+
+_command_exists() {
+    command -v "$1" 1>/dev/null 2>&1
+}
+
+
+# Avoid bad mistakes and show what happens
+alias cp="cp --interactive --verbose"
+alias ln='ln --interactive --verbose'
+alias mv='mv --interactive --verbose'
+alias rm='rm -I --preserve-root --verbose'
+
+
+# Faster directory switching
+alias cd..='cd ..'
+alias ..='cd ..'
+alias ...='cd ../..'
+alias ....='cd ../../..'
+alias .....='cd ../../../..'
+
+
+# Convenient defaults
+alias mkdir='mkdir -p'
+alias md='mkdir'
+alias rmdir='rmdir --parents --verbose'
+alias rd='rmdir'
+
+
+# Convenient grepping
+alias grep='grep --color=auto --exclude-dir={.cache,\*.egg-info,.git,.nox,.tox,.venv}'
+alias egrep='egrep --color=auto --exclude-dir={.cache,\*.egg-info,.git,.nox,.tox,.venv}'
+alias fgrep='fgrep --color=auto --exclude-dir={.cache,*.egg-info,.git,.nox,.tox,.venv}'
+
+
+# Convenient searching
+alias fdir='find . -type d -name'
+alias ffile='find . -type f -name'
+
+
+# Convenient listings
+alias ls='ls --classify --color=auto --group-directories-first --human-readable --no-group --time-style=long-iso'
+alias la='ls --almost-all'
+alias lal='la -l'
+alias ll='ls -l'
+alias l.='ls --directory .*'
+alias ll.='l. -l'
+
+
+# More convenience with various other file-related utilities
+alias df='df --human-readable'
+alias du='du --human-readable'
+alias diff='diff --color=auto --unified'
+_command_exists colordiff && alias diff='colordiff --unified'
+alias free='free --human --total'
+alias less='less --chop-long-lines --ignore-case --LONG-PROMPT --no-init --status-column --quit-if-one-screen'
+alias more='less'
+alias tree='tree -C --dirsfirst'