Initial image support

* png: add missing filters, various decoder fixes
* term: fix kitty response interpretation, add support for kitty image
  detection
* buffer, pager: initial image display support

Emphasis on "initial"; it only "works" with kitty output and PNG input.
Also, it's excruciatingly slow, and repaints images way too often.

Left undocumented intentionally it for now, until it actually becomes
useful.  In the meantime, adventurous users can find out themselves why:

[[siteconf]]
url = "https://.*"
images = true

2 files changed, 11 insertions, 2 deletions

diff --git a/src/io/bufreader.nim b/src/io/bufreader.nim
index 6de269ac..3ee36208 100644
--- a/src/io/bufreader.nim
+++ b/src/io/bufreader.nim
@@ -6,6 +6,7 @@ import std/tables
 
 import io/dynstream
 import types/blob
+import types/color
 import types/formdata
 import types/opt
 import types/url
@@ -53,6 +54,7 @@ proc sread*(reader: var BufferedReader; part: var FormDataEntry)
 proc sread*(reader: var BufferedReader; blob: var Blob)
 proc sread*[T](reader: var BufferedReader; o: var Option[T])
 proc sread*[T, E](reader: var BufferedReader; o: var Result[T, E])
+proc sread*(reader: var BufferedReader; c: var RGBAColor) {.inline.}
 
 proc readData(reader: var BufferedReader; buffer: pointer; len: int) =
   assert reader.bufIdx + len <= reader.buffer.len
@@ -198,3 +200,6 @@ proc sread*[T, E](reader: var BufferedReader; o: var Result[T, E]) =
       o.err(e)
     else:
       o.err()
+
+proc sread*(reader: var BufferedReader; c: var RGBAColor) =
+  reader.sread(uint32(c))
diff --git a/src/io/bufwriter.nim b/src/io/bufwriter.nim
index 75da4190..0957d3e8 100644
--- a/src/io/bufwriter.nim
+++ b/src/io/bufwriter.nim
@@ -6,11 +6,11 @@ import std/sets
 import std/tables
 
 import io/dynstream
-
 import types/blob
+import types/color
 import types/formdata
-import types/url
 import types/opt
+import types/url
 
 type BufferedWriter* = object
   stream: DynStream
@@ -77,6 +77,7 @@ proc swrite*(writer: var BufferedWriter; part: FormDataEntry)
 proc swrite*(writer: var BufferedWriter; blob: Blob)
 proc swrite*[T](writer: var BufferedWriter; o: Option[T])
 proc swrite*[T, E](writer: var BufferedWriter; o: Result[T, E])
+proc swrite*(writer: var BufferedWriter; c: RGBAColor) {.inline.}
 
 proc writeData(writer: var BufferedWriter; buffer: pointer; len: int) =
   let targetLen = writer.bufLen + len
@@ -181,3 +182,6 @@ proc swrite*[T, E](writer: var BufferedWriter; o: Result[T, E]) =
   else:
     when not (E is void):
       writer.swrite(o.error)
+
+proc swrite*(writer: var BufferedWriter; c: RGBAColor) =
+  writer.swrite(uint32(c))