Make the PDF slightly more friendly towards Adobe Reader

I have no idea which values should I use to embed the font in a way
that Adobe can open it, but at least now it works if you have the
font installed.
All the other PDF viewers can read the file just fine though.

src/export.rs

@@ -21,9 +21,14 @@ pub fn to_pdf(puzzles: &Vec<config::Puzzle>, number_of_pages: i32, lang: &lang::
     // Create a font descriptor dictionary object
     let font_stream_id = doc.add_object(font_stream);
     let font_descriptor_dict = dictionary! {
-        "Type" => "TrueType",
-        "FontName" => "Chess-Alpha",
+        "Type" => "FontDescriptor",
+        "FontName" => "Chess Alpha",
         "FontFile2" => font_stream_id,
+        //"FontWeight" => "Medium",
+        //"Ascent" => 0,
+        //"Descent" => 0,
+        //"StemV" => 100,
+        "FontBBox" => vec![0.into(),0.into(), 1024.into(), 1024.into()],
         "Flags" => 33,
     };
     let font_descriptor_id = doc.add_object(font_descriptor_dict);
@@ -37,12 +42,13 @@ pub fn to_pdf(puzzles: &Vec<config::Puzzle>, number_of_pages: i32, lang: &lang::
     let font_dict = dictionary! {
         "Type" => "Font",
         "Subtype" => "TrueType",
-        "BaseFont" => "Chess-Alpha",
-        "FirstChar" => 0,
+        "BaseFont" => "Chess Alpha",
+        "FirstChar" => 32,
         "LastChar" => 255,
-        "Widths" => vec![1000.into();256],
+        "Widths" => vec![1024.into();256],
         "FontDescriptor" => font_descriptor_id,
         "Encoding" => doc.add_object(encoding),
+        "Length1" => font_data.len() as i32
     };
 
     let font_id = doc.add_object(font_dict);
@@ -66,7 +72,7 @@ pub fn to_pdf(puzzles: &Vec<config::Puzzle>, number_of_pages: i32, lang: &lang::
     let resources_id = doc.add_object(dictionary! {
         // fonts are actually triplely nested dictionaries. Fun!
         "Font" => dictionary! {
-            "Chess-Alpha" => font_id,
+            "Chess Alpha" => font_id,
             "Regular" => regular_font_id,
         },
     });
@@ -273,7 +279,7 @@ fn gen_diagram_operations(index: usize, puzzle: &config::Puzzle, start_x:i32, st
             Operation::new("ET", vec![]),
 
             Operation::new("BT", vec![]),
-            Operation::new("Tf", vec!["Chess-Alpha".into(), 25.into()]),
+            Operation::new("Tf", vec!["Chess Alpha".into(), 25.into()]),
             Operation::new("rg", vec![0.into(),0.into(),0.into()]),
             Operation::new("Td", vec![start_y.into(), start_x.into()]),
             ];