add emulation bootstrap target in makefile & update README

Makefile

@@ -30,6 +30,11 @@ clean:
 cleanthirdparty:
 	cd koreader-base && make cleanthirdparty
 
+setupemu:
+	test -d libs-emu || ln -s koreader-base/libs-emu ./
+	test -d fonts || ln -s koreader-base/fonts ./
+	test -d data || ln -s koreader-base/data ./
+
 customupdate: koreader-base/koreader-base koreader-base/extr
 	# ensure that the binaries were built for ARM
 	file koreader-base/koreader-base | grep ARM || exit 1

README.md

@@ -47,12 +47,15 @@ Follow these steps:
 * run `make thirdparty`. This will build MuPDF (plus the libraries it depends
   on), libDjvuLibre, CREngine, libk2pdfopt and Lua.
 
-* run `make`. This will build the koreader application
+* run `make`. This will build the koreader application (see below if you want
+  to build in emulation mode so you can test it on PC)
 
 
 Running
 =======
 
+In real eink devices
+---------------------
 The user interface is scripted in Lua. See "reader.lua".
 It uses the Linux feature to run scripts by using a corresponding line at its
 start.
@@ -66,3 +69,24 @@ usage notes.  The reader.lua script can also show a file chooser: it will do
 this when you call it with a directory (instead of a file) as first argument.
 
 
+In emulator
+-----------
+You need to first compile koreader-base in emulation mode.
+  * If you have built koreader in real mode before, you need to clean it up:
+```
+make clean
+make cleanthirdparty
+```
+  * Then compile with emulation mode flag:
+```
+EMULATE_READER_W=600 EMULATE_READER_H=800 EMULATE_READER=1 make
+```
+  * You may want to see README.md in koreader-base for more information.
+
+Next run `make setupemu` to setup basic runtime environment needed by emulation
+mode.
+
+Last, run the emulator with following command:
+```
+./koreader-base/koreader-base reader.lua -d ./
+```