Fix DLDIR default directory. Closes ilikenwf#162

 * Set /var/cache/apt/apt-fast as default directory over
   /var/cache/apt/archives/apt-fast .

   Prevents apt warning:

    W: Problem unlinking the file apt-fast - pkgAcquire::Clean (21: Is a directory)

 * Update README and fix language in config file.

README.md

@@ -232,9 +232,9 @@ apt-fast uses APT's proxy settings (`Acquire::http::proxy`, `Acquire::https::pro
 
 ### Download folder ###
 ```sh
-DLDIR='/var/cache/apt/archives/apt-fast'
+DLDIR='/var/cache/apt/apt-fast'
 ```
-Directory where apt-fast downloads the packages.
+Directory where apt-fast (temporarily) downloads the packages.
 
 
 ### APT archives cache ###

apt-fast

@@ -124,9 +124,9 @@ eval "$(apt-config shell APTCACHE Dir::Cache::archives/d)"
 # Check if APT config option Dir::Cache::archives::apt-fast-partial is set.
 eval "$(apt-config shell apt_fast_partial Dir::Cache::archives::apt-fast-partial/d)"
 if [ -z "$apt_fast_partial" ]; then
-  eval "$(apt-config -o Dir::Cache::archives::apt-fast-partial=apt-fast shell DLDIR Dir::Cache::archives::apt-fast-partial/d)"
+  DLDIR="$(realpath "${APTCACHE}/../apt-fast")"
 else
-  eval "$(apt-config shell DLDIR Dir::Cache::archives::apt-fast-partial/d)"
+  DLDIR="${apt_fast_partial}"
 fi
 # Currently not needed.
 eval "$(apt-config shell LISTDIR Dir::State::lists/d)"

apt-fast.conf

@@ -121,8 +121,7 @@
 #_DOWNLOADER='aria2c --no-conf -c -j ${_MAXNUM} -x ${_MAXCONPERSRV} -s ${_SPLITCON} --min-split-size=${_MINSPLITSZ} --stream-piece-selector=${_PIECEALGO} -i ${DLLIST} --connect-timeout=600 --timeout=600 -m0 --header "Accept: */*"'
 
 
-# Download temp folder for Downloadmanager
-# example /tmp/apt-fast. Standard is /var/cache/apt-fast
+# Temporary download folder for download manager.
 #
 # Default: /var/cache/apt/apt-fast
 #