Add -pin-last option to keep the last-used entry first

[CyberShadow]

This allows quickly re-running the last command by simply running rofi and pressing Enter.

The last commit enables the new option by default, but I can drop it at your discretion.

[codecov-io]

Codecov Report

Merging #651 into next will increase coverage by 0.04%. The diff coverage is 100%.

@@            Coverage Diff             @@
##             next     #651      +/-   ##
==========================================
+ Coverage   73.08%   73.12%   +0.04%     
==========================================
  Files          37       37              
  Lines        9862     9877      +15     
==========================================
+ Hits         7208     7223      +15     
  Misses       2654     2654

Impacted Files	Coverage Δ
source/xrmoptions.c	63.61% <ø> (ø)	:arrow_up:
test/history-test.c	100% <100%> (ø)	:arrow_up:
source/history.c	86.33% <100%> (+0.62%)	:arrow_up:

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[CyberShadow]

Updated and rebased on next branch.