Add install arguments to not set up {,f}path

Fixes marlonrichert#205

Test:

```russell@zip:~ ❯ cat test.zsh
t() {
    path=(/usr/bin /bin)
    fpath=()
    echo --
    echo znap install "$@"
    znap install "$@"
    echo path = $#path , fpath = $#fpath
}

t asdf-vm/asdf --no-path --no-fpath
t --no-path --no-fpath asdf-vm/asdf
t --no-path asdf-vm/asdf
t asdf-vm/asdf --no-path
t --no-fpath asdf-vm/asdf
t asdf-vm/asdf --no-fpath
t asdf-vm/asdf
t asdf-vm/asdf --no-such-arg
russell@zip:~ ❯ source test.zsh
--
znap install asdf-vm/asdf --no-path --no-fpath
path = 2 , fpath = 0
--
znap install --no-path --no-fpath asdf-vm/asdf
path = 2 , fpath = 0
--
znap install --no-path asdf-vm/asdf
path = 2 , fpath = 1
--
znap install asdf-vm/asdf --no-path
path = 2 , fpath = 1
--
znap install --no-fpath asdf-vm/asdf
path = 3 , fpath = 0
--
znap install asdf-vm/asdf --no-fpath
path = 3 , fpath = 0
--
znap install asdf-vm/asdf
path = 3 , fpath = 1
--
znap install asdf-vm/asdf --no-such-arg
znap clone: invalid argument '--no-such-arg'
Usage: znap clone ( <user>/<repo> | <url> ) ...
Download repos in parallel.
path = 2 , fpath = 0
```

completions/_znap

@@ -23,9 +23,6 @@ case $words[1] in
   ( clone )
     _arguments : '*:remote repository:_urls'
   ;;
-  ( compdef )
-    _arguments : ':function name:' ': :_default'
-  ;;
   ( compile )
     _arguments : ': :_default'
   ;;
@@ -42,7 +39,10 @@ case $words[1] in
     _arguments : ': :->repos' ':pattern:'
   ;;
   ( install )
-    _arguments : '*:remote repository:_urls'
+    _arguments : \
+      "--no-fpath[don't update fpath with completions or functions]" \
+      "--no-path[don't update PATH with binaries]" \
+      '*:remote repository:_urls'
   ;;
   ( multi )
     _arguments : ': :_default'

functions/.znap.install

@@ -1,6 +1,6 @@
 #!/bin/zsh
 # install executables & completion functions
-# args: <repo> ...
+# args: <repo> [--no-path] [--no-fpath] ...
 emulate -L zsh; setopt $_znap_opts
 zmodload -Fa zsh/files b:zf_ln b:zf_mkdir
 
@@ -10,12 +10,14 @@ if (( $# < 1 )); then
   return $(( sysexits[(i)USAGE] + 63 ))
 fi
 
+local -A opts
+zparseopts -A opts -E -D -- -no-path -no-fpath
+
 .znap.clone $@ ||
     return
 
 local REPLY=
 private -aU funcfiles=()
-private bindir=~/.local/bin
 private d='' link='' pat='[[:alnum:]][[:alnum:]_-]#[[:alnum:]]'
 
 local -a repos=()
@@ -26,14 +28,18 @@ private repo=
 for repo in $repos; do
   repo=~[$repo]
 
-  path=(
-      $repo/{,bin/}$~pat(N*:h)
-      $path[@]
-  )
-  fpath=(
-      $repo/{,{[Cc]ompletions,[Ss]rc,zsh}/($~pat/)#}_$~pat(N^/:h)
-      $fpath
-  )
+  if ! (( $+opts[--no-path] )) ; then
+    path=(
+        $repo/{,bin/}$~pat(N*:h)
+        $path[@]
+    )
+  fi
+  if ! (( $+opts[--no-fpath] )) ; then
+      fpath=(
+          $repo/{,{[Cc]ompletions,[Ss]rc,zsh}/($~pat/)#}_$~pat(N^/:h)
+          $fpath
+      )
+  fi
 
   funcfiles=( $repo/{,[Ff]unctions}/($~pat/)#}$~pat(N^/) )
   (( $#funcfiles )) &&