added <FG> command and special Q-Register "$" to set and get the current working directory

 * FG stands for "Folder Go"
 * FG behaves similar to a Unix shell `cd`.
   Without arguments, it changes to the $HOME directory.
 * The $HOME directory was previously only used by $SCITECOCONFIG on Unix.
   Now it is documented on its own, since the HOME directory should also
   be configurable on Windows - e.g. to adapt SciTECO to a MinGW or Cygwin
   installation.
   HOME is initialized just like the other environment variables.
   This also means that now, the $HOME Q-Register is always defined
   and can be used by platform-agnostic macros.
 * FG uses a new kind of tab-completion: for directories only.
   It would be annoying to complete the FG command after every
   directory, so this tab-completion does not close the command
   automatically. Theoretically, it would be possible to close
   the command after completing a directory with no subdirectories,
   but this is not supported currently.
 * Filename arguments are no longer completed with " " if {} escaping
   is in place as this brings no benefit. Instead no completion character
   is inserted for this escape mode.
 * "$" was mapped to the current directory to support an elegant way to
   insert/get the current directory.
   Also this allows the idiom "[$ FG...new_dir...$ ]$" for changing
   the current directory temporarily.
 * The Q-Register stack was extended to support restoring the string
   part of special Q-Registers (that overwrite the default functionality)
   when using the "[$" and "]$" commands.
 * fixed minor typos (american spelling)

1 files changed, 17 insertions, 8 deletions

diff --git a/doc/sciteco.1.in b/doc/sciteco.1.in
index 3129189..0f091db 100644
--- a/doc/sciteco.1.in
+++ b/doc/sciteco.1.in
@@ -145,23 +145,32 @@ batch mode processing.
 .SH ENVIRONMENT
 .
 Before \*(ST executes any macro, all of the variables in the process
-environment are inserted into the global
-.I Q-Register
-table.
+environment are inserted into the global Q-Register table.
 A dollar sign is prepended before each variable name, so that for
 instance the variable \(lqHOME\(rq can be examined by macros by
 reading the string-content of Q-Register \(lq$HOME\(rq.
+Changes to these Q-Registers are currently not applied to
+the corresponding environment variables.
+.LP
 The following environment variables are initialized with default
 values by \*(ST if they are unset:
 .TP
+.B HOME
+Home directory of the current user.
+This may be used e.g. by the \fBFG\fP command.
+If unset, it defaults to the current user's home directory
+as set by
+.BR passwd (5)
+or as determined by other platform-dependent means.
+Initialization of this variable ensures that the
+\(lq$HOME\(rq Q-Register is available even on Windows
+and the home directory can always be re-configured.
+.TP
 .B SCITECOCONFIG
 Path where \*(ST looks for configuration files.
 For instance, this is the path of the default profile.
 If unset, this variable defaults to the \fBHOME\fP
-environment variable on UNIX/Linux.
-If \fBHOME\fP is unset, it defaults to the current user's
-home directory as set by
-.BR passwd (5).
+environment variable on Unix.
 On Windows, this variable defaults to the location of the
 \*(ST program executable, so that \*(ST is self-contained
 on Windows.
@@ -181,7 +190,7 @@ defaults to the standard library installation path at
 .BR "@scitecolibdir@" .
 .
 .LP
-Both the \fBSCITECOCONFIG\fP and \fBSCITECOPATH\fP environment
+The \fBHOME\fP, \fBSCITECOCONFIG\fP and \fBSCITECOPATH\fP environment
 variables are canonicalized to absolute paths.
 Therefore it is possible to define them relative to the
 working directory of \*(ST when it starts up while macros