Implement textexpander's macros

This MR implements "macros", proposed in issue #5 (closed), which allow for more complex actions than just simple text insertion. Specifically, it implements:

• %key:⟨keysym⟩%¹, which simulates pressing that key
• %|², the "cursor position macro", moves the cursor to that part of the expansion after the text is expanded.
• %\³, which selects from wherever %| was to "here".

Closes #5 (closed).

To Draft

• %key:⟨keysym⟩%¹, which simulates pressing that key
• %|², the "cursor position macro", moves the cursor to that part of the expansion after the text is expanded.
• %\³, which selects from wherever %| was to "here".
• %%³, which expands a single percent character (escape) (if needed)
  Wasn't needed (see thread)
• Error checking code that returns an error when %| and %\ aren't the last-seen macros
• Expand the README describing how to use these new macros

To Test

View Test Cases

macro_key_test_1: "Key[A]: %key:A%, Key[B]: %key:B%"
macro_key_test_2: "-->Key[TAB]: %key:Tab%<--"
macro_key_test_3: MyUserName%key:Tab%MyPassWord
cursor_test_1: "%|<--- Cursor should be here"
cursor_test_2: "Cursor --> %| <----"
cursor_test_3: |2-
  My Name is Frank
  My Name is %|Joseph
  My Name is Abigail
highlight_test_1: '--> %\highlighted'
highlight_test_2: 'The %|word%\ "word" should be highlighted'
invalid_macro_test_1: 'Key[A]: %key:A%, Cursor: %|, Key[B]: %key:B%'
invalid_macro_test_2: 'Key[A]: %key:A%, Cursor: %|, Key[B]: %key:B%, Highlight: %\'

• %key:⟨keysym⟩%¹
• %|²
  • Passes cursor_test_1
  • Passes cursor_test_2
  • Passes cursor_test_3
• %\³
  • Passes highlight_test_1
  • Passes highlight_test_2
• %%³ Wasn't needed (see thread)
• Error checking code that returns an error when %| and %\ aren't the last-seen macros
  • Passes invalid_macro_test_1
  • Passes invalid_macro_test_2

To Debug

• It looks like texpander inserts a newline after the snippet now for one line snippets, which I should fix.
• It also looks like xdotool isn't quite working yet for key.
• After being read, the macro_queue array ends up having a ton of weird whitespace in it
• Sometimes text is being sliced off too early by the macro (see below thread)
• It looks like partitions after the first aren't correctly being inserted? (see below thread)

View State Diagram

stateDiagram
proc : Start processing the macros
mkq : make a priority queue to put the macros in
c1 : Still macros in text?
cm : Consider the macro closest to the start of the text
ri : Push where it starts in the text onto the queue 
sr : Store that number somewhere
dl : Delete the macro's text

% toplevel
[*] --> mkq
mkq --> proc

% Process Macros
proc --> c1
c1 -->  c2 : [No]
c1 --> cm : [Yes]
cm --> ri
ri --> sr 
sr --> dl
dl --> c1

% Execute Macros
pstrst : Paste rest of text
c2     : Macro Queue Empty?
pm     : Pop a macro from the queue
pst    : Paste text up until the macro's index
ex     : Execute the macro
c2 --> pstrst : [Yes]
pstrst --> [*]
c2 --> pm : [No]
pm --> pst
pst --> ex
ex --> c2
note right of mkq
Priority will be based off of the closeness 
to beginning of text, and the order of 
execution. The order of execution should 
be as follows.
1. %key
2. %|
3. %\
end note