Updated filepicker.lua and adding documentation

Effectively rendering openfile.lua completely obsolete, which is why it
was deleted. filepicker.lua is now way smarter, handles file creation
and has a documentation file in LDoc.

doc/config.ld

@@ -11,7 +11,7 @@ format = "markdown"
 plain = true
 
 -- Input files
-topics = "../README.md"
+topics = {"../README.md", "filepicker.md"}
 file = "../source/"
 examples = "../sdcard/3ds/ctruLua/examples/"
 manual_url = "file://../libs/lua-5.3.1/doc/manual.html"

doc/filepicker.md

@@ -0,0 +1,93 @@
+# filepicker
+## filePicker([workingDirectory[, bindings[, callbacks[, ...]]]])
+### Argument: workingDirectory
+The directory that shows up first in the file browser.
+If this is nil, ctr.fs.getDirectory() is used.
+The recommended form is sdmc:/path/ or romfs:/path/, but it can be a simple /path/ instead.
+#### Possible values
+- string
+- nil
+
+### Argument: bindings
+A table, list of filetypes and key bindings related to these filetypes.
+#### Format
+```
+{
+  __default, __directory, [Lua regexp] = {
+    [keys from ctr.hid.keys()] = {
+      function
+      string
+    }...
+    __name = string
+  }...
+}
+```
+
+The Lua regexp is matched against the filename to determine if it is of this type.
+__directory is the "file type" for directories
+__default is the "file type" for files that cannot be matched with any other.
+  Also, every other type inherits the values it doesn't define from __default.
+A file type contains the human-readable name (__name) of the type, displayed on the bottom screen,
+  as well as an optional binding for each key.
+The optional binding is formed of an anonymous function, followed by the key's label to be displayed on the bottom screen,
+  if the label is nil, the key isn't displayed but still bound.
+
+The function is defined as-is:
+##### function(externalConfig, selected, bindingPattern, bindingKey)
+externalConfig.workingDirectory is the active directory for filePicker, doesn't necessarily match ctrµLua's.
+externalConfig.bindings, externalConfig.callbacks and externalConfig.additionalArguments all are the arguments passed to filePicker,
+  starting from position 2.
+externalConfig.fileList is the list of files currently displayed by filePicker, in the same format as is returned by ctr.fs.listDirectory().
+selected.inList is the absolute position of the cursor in externalConfig.fileList
+selected.offset is the number of items skipped for display from fileList
+bindingPattern is the [Lua regexp] defined earlier, and bindingKey the [key] that triggered this event.
+This function may return the same thing as filePicker itself (Defined later here), or nothing. If it returns nothing,
+filePicker will keep running, if it returns the same returns as filePicker, filePicker will exit, returning these values.
+
+#### Notes
+Sane defaults are set if you did not set them otherwise:
+__default.x quits filePicker, returning the current directory, "__directory", nil and "x". See the returns to understand what this means.
+__directory.a changes directories to that directory.
+
+### Argument: callbacks
+A table defining the callbacks ran at the end of each of the equivalent phases.
+#### Format
+```      
+{
+  drawTop, drawBottom, eventHandler = function
+}
+```
+All of these take the following parameters: (externalConfig, selected)
+They have the meaning defined earlier.
+
+#### Notes
+Although drawTop and drawBottom are ran at the end of their respective functions,
+eventHandler is not, as it cannot be without being run repeatedly, so it's run at the beginning of
+the ACTUAL eventHandler instead of its end.
+
+### Argument: ...
+Additional parameters. All of these are aggregated orderly in externalConfig.additionalArguments and passed around as explained earlier.
+They have no specific meaning unless defined so by event handling functions.
+
+### Return 1: selectedPath
+The path selected by the either, may or may not have the sdmc:/romfs: prefix, depending on your input.
+A string.
+
+### Return 2: bindingPattern
+The pattern the file matched to. You can use this to know exactly which kind of file you're dealing with
+A string.
+
+### Return 3: mode
+Included handlers may have it be "open", in case you're opening an existing file, "new" in case the user wants to create a new file,
+Or nil. A "nil" is assumed to mean that the user didn't pick anything.
+A string or nil.
+
+### Return 4: key
+The key that triggered the event that made filePicker exit.
+A string.
+
+## Included event handlers you have available are:
+- filepicker.changeDirectory - The name is on the tin, change workingDirectory to the active element and refresh the file list for that path.
+- filepicker.openFile - Quits and returns as described by this document based on the active element.
+- filepicker.newFile - Prompts the user to input a file name manually, relative to the current working directory, and with FAT-incompatible characters excluded. Quits and returns that.
+- filepicker.nothing - Do nothing and keep on running. Literally. This is used as a plug to enable an action for all (or a certain type) but files of a certain type (or more precise than the initial type).