lua5.1 compatibility

[smarek]

This directly provides compiler functions, required by updated Lua runtime, see kaitai-io/kaitai_struct_lua_runtime#5 for reference

This PR will need the tests to be re-compiled, since Lua 5.1 does not support unicode escape sequence, i've switched to UTF8 decimal encoding, this fixes tests StrEncodings and StrEncodingsDefault (along with SJIS support added in Lua runtime)

Example diff over kaitai_struct_tests after merging this looks like this

> git diff spec/lua/test_s*
diff --git a/spec/lua/test_str_encodings.lua b/spec/lua/test_str_encodings.lua
index d0e0531f..26b8c8e6 100644
--- a/spec/lua/test_str_encodings.lua
+++ b/spec/lua/test_str_encodings.lua
@@ -10,7 +10,7 @@ function TestStrEncodings:test_str_encodings()
     local r = StrEncodings:from_file("src/str_encodings.bin")
 
     luaunit.assertEquals(r.str1, "Some ASCII")
-    luaunit.assertEquals(r.str2, "\u{3053}\u{3093}\u{306b}\u{3061}\u{306f}")
-    luaunit.assertEquals(r.str3, "\u{3053}\u{3093}\u{306b}\u{3061}\u{306f}")
-    luaunit.assertEquals(r.str4, "\u{2591}\u{2592}\u{2593}")
+    luaunit.assertEquals(r.str2, "\227\129\147\227\130\147\227\129\171\227\129\161\227\129\175")
+    luaunit.assertEquals(r.str3, "\227\129\147\227\130\147\227\129\171\227\129\161\227\129\175")
+    luaunit.assertEquals(r.str4, "\226\150\145\226\150\146\226\150\147")
 end
diff --git a/spec/lua/test_str_encodings_default.lua b/spec/lua/test_str_encodings_default.lua
index 04e6851b..18172060 100644
--- a/spec/lua/test_str_encodings_default.lua
+++ b/spec/lua/test_str_encodings_default.lua
@@ -10,7 +10,7 @@ function TestStrEncodingsDefault:test_str_encodings_default()
     local r = StrEncodingsDefault:from_file("src/str_encodings.bin")
 
     luaunit.assertEquals(r.str1, "Some ASCII")
-    luaunit.assertEquals(r.rest.str2, "\u{3053}\u{3093}\u{306b}\u{3061}\u{306f}")
-    luaunit.assertEquals(r.rest.str3, "\u{3053}\u{3093}\u{306b}\u{3061}\u{306f}")
-    luaunit.assertEquals(r.rest.str4, "\u{2591}\u{2592}\u{2593}")
+    luaunit.assertEquals(r.rest.str2, "\227\129\147\227\130\147\227\129\171\227\129\161\227\129\175")
+    luaunit.assertEquals(r.rest.str3, "\227\129\147\227\130\147\227\129\171\227\129\161\227\129\175")
+    luaunit.assertEquals(r.rest.str4, "\226\150\145\226\150\146\226\150\147")
 end
diff --git a/spec/lua/test_switch_manual_int_size_eos.lua b/spec/lua/test_switch_manual_int_size_eos.lua
index 36001a93..7163a227 100644
--- a/spec/lua/test_switch_manual_int_size_eos.lua
+++ b/spec/lua/test_switch_manual_int_size_eos.lua
@@ -18,7 +18,7 @@ function TestSwitchManualIntSizeEos:test_switch_manual_int_size_eos()
     luaunit.assertEquals(r.chunks[2].body.body.entries, {"AAAA", "BBBB", "CCCC"})
 
     luaunit.assertEquals(r.chunks[3].code, 0x33)
-    luaunit.assertEquals(r.chunks[3].body.body, "\x10\x20\x30\x40\x50\x60\x70\x80")
+    luaunit.assertEquals(r.chunks[3].body.body, "\16\32\48\64\80\96\112\128")
 
     luaunit.assertEquals(r.chunks[4].code, 0xff)
     luaunit.assertEquals(r.chunks[4].body.body, "")

[smarek]

Well I'm happy you appreciated my work, i've updated the commit to reflect on your points.

Also it would be great, if the PRs on this repository built with Travis, so we know the PR is working well (eg. the mentioned conflict about used Java APIs when building ScalaJS build for JavaScript).