make launcher autocomplete case insensitive

this will exclude entries that have legitimate capital letters in them,
but the only such victim right now is RemoteFortressReader, which is a
dev tool and is hidden by default, so I'm not that worred about it. We
intend for all tools to be lower case, so this shound't cause problems
in the future. (Hi future person looking at this, trying to debug the
problem it causes)

changelog.txt

@@ -63,6 +63,7 @@ Template for new versions:
 - `gui/mass-remove`: can now remove zones
 - `gui/mass-remove`: can now cancel removal for buildings and constructions
 - `fix/stuck-instruments`: now handles instruments that are left in the "in job" state but that don't have any actual jobs associated with them
+- `gui/launcher`: make autocomplete case insensitive
 
 ## Removed
 

gui/launcher.lua

@@ -106,7 +106,7 @@ end
 local function get_first_word(text)
     local word = text:trim():split(' +')[1]
     if word:startswith(':') then word = word:sub(2) end
-    return word
+    return word:lower()
 end
 
 local function get_command_count(command)